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A 1400 year multi-proxy record of hydrologic variability in the Gulf of Mexico

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Title:
A 1400 year multi-proxy record of hydrologic variability in the Gulf of Mexico exploring ocean-continent linkages during the late Holocene
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English
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Flannery, Jennifer A
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University of South Florida
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Subjects / Keywords:
Pigmy Basin
Marine sediments
Paleoclimate
Ocean-continent interactions
Mississippi River
Dissertations, Academic -- Marine Science -- Masters -- USF   ( lcsh )
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non-fiction   ( marcgt )

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Abstract:
ABSTRACT: Late Holocene climate variability includes the Little Ice Age (LIA, 450-150 BP) and the Medieval Warm Period (MWP, 1100-700 BP) that are characterized by contrasting hydrologic and thermal regimes. The degree of interaction between the North American continent and the ocean during these two abrupt climate events is not well known. Marine sedimentary records from basins proximal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changing climate and hydrologic conditions. The Pigmy Basin in the northern Gulf of Mexico is ideally situated to record inputs from the Mississippi River and to relate these inputs to changing hydrologic conditions over North America during the LIA and MWP. Hydrologic variability recorded over the North America continent is directly dependent on the moisture balance (E/P) over the sub-tropical Gulf of Mexico (a major source of moisture to the North America continent). Warm, moist air masses from the south interact with cold/dry air masses from the north over the North American continent to produce storm fronts. Increased evaporation over the Gulf of Mexico leads to enhanced precipitation over the North American continent, due to the intensification of atmospheric circulation, which influences meridional moisture flux from the Gulf of Mexico to the North American continent. This study focuses on the sedimentary record spanning the last 1400 years and utilizes a multi-proxy approach incorporating organic and inorganic geochemical analyses to define intervals of varying continental inputs and to assess changes in the moisture balance (E-P) within the Gulf of Mexico.
Thesis:
Thesis (M.S.)--University of South Florida, 2008.
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Includes bibliographical references.
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by Jennifer A. Flannery.
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Title from PDF of title page.
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Document formatted into pages; contains 174 pages.
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Includes vita.

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A 1400 Year Multi-Proxy Record of Hydrologic Variab ility in the Gulf Of Mexico: Exploring Ocean-Continent Linkages During the Late Holocene by Jennifer A. Flannery A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science College of Marine Science University of South Florida Major Professor: David J. Hollander, Ph.D. Benjamin P. Flower, Ph.D. Edward S. VanVleet, Ph.D. Date of Approval: June 24, 2008 Keywords: Pigmy Basin, marine sediments, paleoclima te, ocean-continent interactions, Mississippi River Copyright 2008, Jennifer A. Flannery

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Acknowledgements Several faculty members of the College of Marine S cience have been paramount to the success of this research. I would like to th ank my advisor, Dr. David Hollander, for making me the best scientist that I can be by havin g high expectations of me, providing encouragement when it was needed most, and always h aving an open door when I specifically needed guidance. Dr. Benjamin Flower e specially helped me with the preparation of conference presentations and brought things to my attention that I would not have realized. Dr. Edward VanVleet provided unb elievable technical assistance; without that, the organic portion of this thesis wo uld not have been possible. Dr. Richard Poore at the USGS served as my USGS funding sponsor Dr. David Hastings at Eckerd College inspired me to apply for an internship I ha d never thought of, which led to this thesis research. Dr. Heather Hill always had a posi tive and a “can-do” attitude, which inspired me to do the same, ultimately leading to m y success as a scientist. Ethan Goddard, Greg Ellis, and Taryn Harvey provided the technical assistance needed to perform the various analyses discussed in this thes is. Julie Richey and A. Nele Meckler provided data. Dr. Jyotika Virmani provided thought on the climatological aspects of this thesis. I cannot express my gratitude towards the “Paleo L ab” in the College of Marine Science. Whether it was technical assistance with i nstrumentation, a deep scientific conversation, or a shoulder to cry on when things b ecame less than favorable, the other members of the lab were always there. For that I am extremely grateful.

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i Table of Contents List of Tables v List of Figures vi Abstract vii 1. Introduction 1 1.1 Research Overview 1 1.2 Modern Mississippi River System 3 1.3 Climate Controls on Mississippi River Terrestr ial Inputs 4 1.3.1 Seasonal/Annual Variability 6 1.3.1.1 Great Plains Low Level Jet 6 1.3.1.2 Air Masses 7 1.3.2 Decadal Variability 9 1.3.2.1 Atlantic Multidecadal Oscillation 9 1.3.2.2 North Atlantic Oscillation 12 1.3.2.3 Solar Variability 13 1.4 The Holocene 14 1.4.1 The Little Ice Age and the Medieval Warm Peri od 14 1.5 Regional Setting 15 1.5.1 Pigmy Basin 15 1.5.2 Gulf of Mexico Climate 18 1.6 Geochemical Approach 18 1.6.1 Field Site and Age Model 18 1.7 Thesis Organization 21 2. Research Methods 24 2.1 Field Site and Sediment Core 24 2.2 Equations 26 2.3 Grain Size Analysis 26 2.4 Physical Parameters 27 2.5 Carbon Concentrations 28 2.5.1 Combustion – Wt % TC 29 2.5.2 Acidification – Wt % CaCO3 29 2.5.3 Wt % TOC and Wt % Insoluble Residues 30 2.6 Bulk Carbon and Nitrogen Isotopes 31 2.7 Titanium 32

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ii 2.8 Molecular Organic Geochemistry 33 2.8.1 Glassware Washing and Solvent Rinsing 33 2.8.2 Silica and Alumina Gel Extraction and Deactiv ation 34 2.8.3 Soxhlet Extraction of Samples – Total Lipid E xtraction 34 2.8.4 Separation of Compound Classes 3 6 2.8.5 Separation of Urea Adducts and Non-Adducts on L1/L2 Fraction 38 2.9 Gas Chromatography 39 2.9.1 L1/L2 Fraction 39 2.10 Deuterium Analysis 40 2.11 Time Series Analysis 41 3. Terrestrial Inputs to the Gulf of Mexico: Explor ing Ocean-Continent Linkages During the Late Holocene 42 3.1 Pigmy Basin Terrestrial Input Records 42 3.1.1 Insoluble Residue 42 3.1.2 Titanium 45 3.1.3 HMW n-alkanes 46 3.2 Linking Mississippi River Terrestrial Input to Gulf of Mexico Changes 47 3.2.1 Wet Intervals 47 3.2.2 Dry Intervals 49 3.3 Periodic Variability 51 3.4 Climate Implications 54 3.5 Summary and Conclusions 55 4. Compound Specific D Analysis of High Molecular Weight N-alkanes as Indicators of North American Hydrologic Variabi lity 57 4.1 Introduction 57 4.1.1 Hydrogen Isotopes 57 4.1.2 Hydrogen Isotopes in Plants 62 4.2 Results and Discussion 64 4.2.1 Influences on n-alkane D Values 66 4.2.2 Metabolic Pathway Influence on n-alkane D Values 68 4.3 Future Work 69 4.4 Summary and Conclusions 70 5. Complementary Analyses of Pigmy Basin Sediments 71 5.1 Abstract 71 5.2 Results and Discussion 72 5.2.1 Grain Size Analysis 72 5.2.2 Physical Parameters 75 5.2.3 Carbon Concentrations 77 5.2.3.1 Total Carbon 77 5.2.3.2 Total Organic Carbon 80 5.2.3.3 Calcium Carbonate 81 5.2.4 Bulk Organic Carbon Isotopes 82

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iii 5.2.5 Bulk Nitrogen Isotopes 86 5.2.6 Low-molecular weight n-alkanes 88 5.3 Summary and Conclusions 90 6. Summary 91 6.1 Climate Variability 91 6.2 Terrestrial Inputs into the Gulf of Mexico 91 6.3 Hydrogen Isotopes of High Molecular n-alkanes from the Pigmy Basin 92 6.4 Complimentary Analyses of Pigmy Basin Sediment s 93 6.5 Future Work 93 References Cited 96 Appendix A: Age Model and Inorganic Analyses 109 Appendix B: Organic Analyses 155 Appendix C: Isotopic Analyses 167 About the Author

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iv List of Tables Table 1 Radiocarbon ages for core PB-BC1 111 Table 2 Bulk Density, wet water content, and porosi ty analyses 114 Table 3 Grain size, phi size, and composition 118 Table 4 Total carbon, total inorganic carbon, calci um carbonate, and insoluble residue concentrations 122 Table 5 Elemental titanium XRF analyses 1 26 Table 6 Total organic carbon concentrations 157 Table 7 High molecular weight n-alkane concentratio ns 161 Table 8 Low molecular weight n-alkane concentration s 164 Table 9 Bulk organic 13C and 15N analyses 169 Table 10 High molecular weight n-alkane D analyses 173

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v List of Figures Figure 1 Map of the Mississippi River drainage bas in with each individual sub-basin outlined 4 Figure 2 Map of average annual rainfall over the U nited States for 2007 5 Figure 3 Schematic of all of the moisture delivery pathways and related air-mass origin over North America 8 Figure 4 AMO index (from Enfield et. al., 2001) 11 Figure 5 Schematic of Mississippi River terrestrial input delivery to the Gulf of Mexico 16 Figure 6 Map of the United States with the Mississi ppi River Basin and Pigmy Basin highlighted 17 Figure 7 Age model constructed for core NPBC and pr ojected onto sub-core PB-BC1E 19 Figure 8 Correlation between Mississippi River disc harge and suspended solids 20 Figure 9 Photograph of extruded half of sediment co re PB-BC1E 25 Figure 10 Terrestrial input records from Pigmy Basi n 44 Figure 11 Insoluble residue terrestrial input recor d compared with sea surface temperature and salinity records from the P igmy Basin and solar variability record 52 Figure 12 Meteoric water line (Craig, 1961) 58 Figure 13 Average D of precipitation in North America 59 Figure 14 D distribution over North America in January 60 Figure 15 D distribution over North America in July 61

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vi Figure 16 Average Annual Relative Humidity over Nor th America 62 Figure 17 HMW n-alkane C25 and C27 D values 65 Figure 18 Physical property records of core PB-BC1E 74 Figure 19 Records of core PB-BC1E composition n 79 Figure 20 Organic proxies from core PB-BC1E 84 Figure 21 North Pigmy Basin box-core foraminifera a ssemblage data 112 Figure 22 Sub-core PB-BC1E foraminifera assemblage data 113

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vii A 1400 Year Multi-Proxy Record of Hydrologic Variab ility in the Gulf of Mexico: Exploring Ocean-Continent Linkages During the Late Holocene Jennifer A. Flannery ABSTRACT Late Holocene climate variability includes the Litt le Ice Age (LIA, 450-150 BP) and the Medieval Warm Period (MWP, 1100-700 BP) that ar e characterized by contrasting hydrologic and thermal regimes. The degree of inter action between the North American continent and the ocean during these two abrupt cli mate events is not well known. Marine sedimentary records from basins proximal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changin g climate and hydrologic conditions. The Pigmy Basin in the northern Gulf of Mexico is i deally situated to record inputs from the Mississippi River and to relate these inputs to changing hydrologic conditions over North America during the LIA and MWP. Hydrologic va riability recorded over the North America continent is directly dependent on the mois ture balance (E/P) over the subtropical Gulf of Mexico (a major source of moisture to the North America continent). Warm, moist air masses from the south interact with cold/dry air masses from the north over the North American continent to produce storm fronts. Increased evaporation over the Gulf of Mexico leads to enhanced precipitation over the North American continent, due to the intensification of atmospheric circulati on, which influences meridional moisture flux from the Gulf of Mexico to the North American continent. This study

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viii focuses on the sedimentary record spanning the last 1400 years and utilizes a multi-proxy approach incorporating organic and inorganic geoche mical analyses to define intervals of varying continental inputs and to assess changes in the moisture balance (E-P) within the Gulf of Mexico.

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1 Chapter 1 Introduction 1.1 Research Overview Understanding the timing of natural hydrologic vari ability (floods and droughts) over North America during the past two millennia is crucial to accurately predict future hydrologic variability in this region. Floods and d roughts occurring over North America may lead to catastrophic and economic societal loss es, since droughts are one of the most damaging climate related hazards to impact society (Woodhouse and Overpeck, 1998). The Dust Bowl of the 1930’s is the most infamous dr ought in the historical record, resulting in a devastating impact on agriculture in the Mississippi River basin, and subsequently, the economy (Schubert et al., 2004). Therefore, the geologic record needs to be examined to determine intervals of floods or droughts that have occurred in this region throughout time. This thesis focuses on understanding the natural hy drologic variability occurring between the North American continent and the Gulf o f Mexico over the Late Holocene, the past 1400 years. Two abrupt climate events, the Little Ice Age (450-150 BP, Mann, 2002a) and the Medieval Warm Period (1100-700 BP, M ann, 2002b) occurred over the late Holocene. Currently, it is poorly understood h ow these contrasting hydrologic and thermal regimes influenced the climate and hydrolog y of North America. Numerous paleoarchives from the Mississippi River drainage b asin document floods or droughts

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2 over the Late Holocene (i.e. Laird et al., 1996; Dean, 1997; Stokes and Sw inehart, 1997; Fritz et al., 2000; Mason et al., 2004; Daniels and Knox, 2005; Sridhar et al., 2006; Miao et al., 2007), but these records reflect a local or regional response to hydrologic variability. Oceanic basins proximal to major rivers are able to record both terrestrial and oceanic inputs, and provide an integrated assessmen t of hydrologic variability. The Pigmy Basin is located in the northwestern Gulf of Mexico near the mouth of the Mississippi River. Thus, marine sediments from the Pigmy Basin should provide an integrated signal of North American hydrologic vari ability. The primary questions addressed in this thesis are in attempt to better u nderstand natural hydrologic variability between the North American continent and the Gulf o f Mexico over the past 1400 years: 1. How has Mississippi River discharge (terrestrial in put) to the Gulf of Mexico varied over the Late Holocene, the last 1400 years? Is the LIA and MWP manifested in these records? 2. Are there any linkages between the records of terre strial input from the Mississippi River to the Gulf of Mexico and Gulf of Mexico records of sea surface temperature and/or salinity? 3. What are climatological factors that control Missis sippi River terrestrial input to the Gulf of Mexico?

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3 A suite of organic and inorganic geochemical analys es on a marine sedimentary sequence from Pigmy Basin, Gulf of Mexico, was util ized to resolve hydrologic variability over the North American continent durin g the Late Holocene. The weight percent of insoluble residues, titanium abundances, and concentrations of high-molecular weight n-alkanes are used to assess Mississippi Riv er terrestrial input to the Gulf of Mexico. Wet and dry conditions on the North Americ an continent are inferred from these data. These records are also compared with se a surface temperature and salinity records from the Pigmy Basin (Richey et al., 2007) to examine any ocean/continent interactions. The influence of solar variability on the terrestrial input records is examined by pairing the records with a radiocarbon record fr om tree rings (Stuiver et al., 1998). The evaporative conditions over North America are r econstructed using deuterium isotopes of the high-molecular weight n-alkanes. 1.2 Modern Mississippi River System The modern Mississippi River system drains 41% of t he area of the 48 contiguous states of the United States (Goni et al., 1998, and references therein). Six smaller subbasins contribute to the general drainage of the Mi ssissippi River basin (www.epa.gov, Figure 1). The Mississippi River system is the pred ominant source of freshwater and sediment to the Gulf of Mexico (Goni et al., 1997). Maximum discharge of the Mississippi River occurs between January and June, with peak flow in April (Gordon and Goni, 2004). Most of the water contributing to Miss issippi River discharge comes from the Ohio Basin, whereas the majority of sediment or iginates in the Missouri Basin (Turner and Rabalais, 2004). Sediment loading from the Mississippi River to the Gulf of

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4 Mexico averages 210 x 1012 g year-1 (Milliman and Meade, 1983). The Mississippi River transports nutrients that enhance primary productiv ity in the Gulf of Mexico (Lohrenz et al., 1990; Redhalje et al., 1994; Turner and Rabala is, 2004). Approximately 50% of the discharged material into the Gulf of Mexico flows t o the west of the Mississippi River delta where it is deposited (U.S. Army and Corps of Engineers, 1974), and the remainder flows east. Transport of grassland soil organic mat ter is associated with the delivery of fine-grained material to the interior Gulf of Mexic o (Goni et al., 1997). Figure 1. (www.usgs.gov) Map of the Mississippi Riv er drainage basin with each individual subbasin outlined. Together, they comprise 41% of the continental United States. The location of the Pigmy Basin in the Gulf of Mexico is also denoted. 1.3 Climate Controls on Mississippi River Terrestri al Inputs Droughts in the Mississippi River basin may occur d uring any season, but since spring and summer are the seasons when most of the rainfall occurs, these are the seasons Covers 41% of contiguous U.S. Pigmy Basin

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5 most sensitive to drought (Woodhouse and Overpeck, 1998). The average annual rainfall throughout the Mississippi River basin is highly va riable (Figure 2). The majority of annual rainfall in the Mississippi River basin occu rs in the eastern part of the basin whereas the western parts of the basin receive the least rainfall (Figure 2, Hirschboeck, 1991). Figure 2. Map of average annual rainfall over the U nited States for 2007. The Mississippi River drainage basin is outlined in black. Modified from www.prism.oregonstate.edu The state of the oceans (both Atlantic and Pacific) can directly or indirectly lead to drought conditions in the Mississippi River basi n by introducing perturbations in the patterns of atmospheric circulation and moisture tr ansport (Trenberth et al., 1988; Trenberth and Guillemot, 1996; Ting and Wang, 1997) The position of the high-pressure

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6 system over the Great Plains is associated with the position and strength of the Bermuda High in the Atlantic Ocean, which is linked to the strength of the Great Plains Low Level Jet (Helfand and Schubert, 1995). When the Bermuda High is in a position farther east and north than normal, the moist air flows around t he high and into the eastern United States, and the Great Plains region remains dry (Fo rman et al., 1995; Mo et al., 1997). When the Bermuda High is in its normal position sou th and west, the moist air flows around the high and into the central United States (Forman et al., 1995; Mo et al., 1997), resulting in precipitation in the Mississippi River drainage basin. 1.3.1 Seasonal/Annual Variability 1.3.1.2 Great Plains Low Level Jet Seasonal precipitation over the Mississippi River basin is well organized into a summer and winter regime (Hsu and Wallace, 1976). D uring boreal spring and summer, the Great Plains Low Level Jet (GPLLJ), transports moisture from the Gulf of Mexico into the central North American continent (Weaver a nd Nigam, 2008). The GPLLJ is a warm-season climatic feature characterized by a win d maximum below 850 hPa (Weaver and Nigam, 2008). The GPLLJ typically develops at n ight, with peak strength in the late night and early morning hours (Ting and Wang, 2006) This is due to supergeostrophic wind speeds resulting from spatially uneven and diu rnally varying heating of terrain slopes, boundary layer frictional effects, and iner tial oscillation of the ageostrophic wind vector (Blackadar, 1957; Wexler, 1961; Holton, 1967 ; Hoxit, 1975). Seasonal strength of the GPLLJ has been shown to be linked to Great Plai ns hydroclimate via moisture fluxes (Helfand and Schubert, 1995; Higgins et al., 1997; Schubert, et al., 1998), and droughts

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7 and floods in the Great Plains region strongly depe nd on the intensity of the GPLLJ (Bell and Janowiak 1995; Mo et al. 1995; Arritt et al. 19 97; Mo and Berbery 2004). The moisture flux from the Gulf of Mexico provides the moisture that feeds the GPLLJ, and therefore plays a major role in precipitation in th e central United States (Higgins et al., 1997). 1.3.1.3 Air-Masses The dominant moisture delivery pathways over the M ississippi River basin originate from three air-mass source regions: the P acific Ocean, the Gulf of Mexico and Atlantic Ocean, and the Arctic region (Figure 3, Hi rschboeck, 1991). Additional moisture delivery pathways may originate during the boreal w inter from air-masses located in the north-central and eastern United States (Bryson and Hare, 1974; Wendland and Bryson, 1981). As seasons change, these moisture pathways a nd the dominant air-mass sources shift, which are important controls on the seasonal ity of average monthly precipitation and streamflow in the continental United States (Hi rschboeck, 1991). The moisture delivery pathways that originate in t he Gulf of Mexico and Atlantic Ocean are predominant in the east and southern Unit ed States, particularly during the spring and summer (Hirschboeck, 1991). These air-ma sses penetrate far into the interior of the continental United States due to a very well -defined Bermuda High system that forms in the western Atlantic Ocean during the warm season (Hirschboeck, 1991) and shuttles warm, humid, unstable maritime tropical ai r-masses onto the continent via anticyclonic circulation (Mo et al., 1997). Seasona l formation/expansion of the Bermuda

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8 High pressure system controls the meridional moistu re flux from the Gulf of Mexico to the Mississippi River basin (Hastenrath, 1984). Figure 3. Schematic of all of the moisture delivery pathways and related air-mass origin over North America. Cold/dry air-masses are represented in blue, and warm, moist air-masses are represented in red.

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9 Moisture-laden air from the Pacific Ocean is delive red to the continental United States by several pathways that shift with the seas ons, reaching 60N during the summer and 35N during the winter. This air enters the int erior United States where the westerlies are the strongest, between 45N and 50N. This air crosses the western mountain ranges (Sierra Nevada and Rocky Mountains) and loses most of its precipitable water vapor and thus has a modified character, which has a drying e ffect when it dominates over the Great Plains during the fall (Hirschboeck, 1991). During fall and winter, the Bermuda High migrates t o a position in the East or Mid-Atlantic (Machel et al., 1998) and becomes less -defined. The influx of air from the Gulf of Mexico and Atlantic Ocean is limited to the Gulf Coast region, and flood potential in the north decreases, with the exceptio n of any late season tropical storm activity (Hirschboeck, 1991). 1.3.2 Decadal Variability 1.3.2.1 Atlantic Multidecadal Oscillation Climate/hydrologic variability that occurs on long er time-scales is critical to consider as an important driver of hydrologic varia bility over North America. The Atlantic Multidecadal Oscillation (AMO) is an index of detrended (to remove any influence of anthropogenic forcing due to greenhous e gas emissions, or natural trend) sea surface temperature anomalies averaged over the Nor th Atlantic Ocean from 0-70N and is an important mode of climate variability (Enfiel d et al., 2001). Fluctuations in the AMO pattern have a cyclicity of roughly 65 years be tween troughs (Schlesinger and Ramankutty, 1994; Mann and Park, 1994) with a 0.4C temperature difference between

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10 peak and trough (Figure 4, Enfield et al., 2001). T he AMO variability is most likely due to internal variations in the thermohaline circulat ion and associated meridional heat transport (Delworth and Mann, 2000; Collins and Sin ha, 2003; Sutton and Hodson, 2003; Knight et al., 2005), and is global in nature (Enfi eld et al., 2001). A negative correlation exists between the phase of the AMO (warm or cold) and the amount of precipitation that falls in the Missi ssippi River basin (Figure 4C, Enfield et al., 2001). During the positive (warm) AMO phase, t he central United States receives below-average precipitation, especially during the summer months (Enfield et al., 2001; Gray et al., 2003). In contrast, during a negative (cool) AMO phase, precipitation in the Mississippi River Basin increases (Enfield et al., 2001; Gray et al., 2003), resulting in enhanced Mississippi River discharge.

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11 Figure 4. (Enfield et al., 2001) (a) AMO index: th e ten-year running mean of detrended Atlantic SSTA north of the equator. (b) Correlation of the A MO index with gridded SSTA over the world ocean (all seasons). The thick contour is zero and thin contours denote the 95% significance level. (c) Correlation of the AMO index with climate divis ion rainfall with the Mississippi basin highlighted by light gray. The larger highlighted c ircles indicate correlations above the 90% significance level. Inset diagram to the right is a blow-up of Florida showing Lake Okeechobee and Florida climate division 4. The colorbar applie s to correlations in both panels.

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12 1.3.2.2 North Atlantic Oscillation The North Atlantic Oscillation (NAO) is a climatic phenomenon in the North Atlantic Ocean resulting from fluctuations in the d ifference between sea-level pressure of the Icelandic Low and the Bermuda High (Fye et al., 2006). The NAO mainly affects winter conditions, where the strength and direction of westerly winds and storm tracks across the North Atlantic is controlled by the NAO (Fye et al., 2006). These storm tracks influence the climate of North America and Europe ( Trewartha, 1981). Atlantic Ocean sea surface temperature regime shif ts are associated with the NAO positive and negative phases (Wallace et al., 1990) Anomalously warm temperatures extend in a band across the central North Atlantic and into the Gulf of Mexico during the NAO positive phase (Fye et al., 2006). Positive NAO anomalies tend to cause wetter conditions in the central United States (Fye et al. 2006). A well-defined Bermuda High system in the Atlantic Ocean in conjunction with st ronger trade winds and increased evaporation in the Gulf of Mexico and Caribbean (Ka pala et al., 1998) leads to positive NAO anomalies. The increased moisture from the Gulf of Mexico is shuttled into the central United States through anticyclonic circulat ion, which favors spring and summer convective precipitation in the central United Stat es (Fye et al., 2006). This sea surface temperature regime reverses to co oler sea surface temperatures in the central Atlantic Ocean, leading to the NAO nega tive phase (Wallace et al., 1990). A weak Bermuda High system and weak trade winds resul t in the negative phase of the NAO, which favors an anomalously cold North America (Kapala et al., 1998). Winter/spring moisture delivery to the central Unit ed States is reduced and relatively dry conditions prevail (Trewartha, 1981; Oglesby, 1991)

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13 1.3.2.3 Solar Variability The 200-year solar cycle (De Vries or Seuss Cycle) is an intense solar cycle, impacting climate (Raspopov et al., 2008). This cyc le has been inferred as a dominant cycle during the Holocene (Vasil’ev et al., 1999). The solar minima (Maunder, Sporer, Wolf) documented over the past millennia are though t to be manifestations of the de Vries cycle (Eddy, 1976). During the Maunder Minimu m (1645-1715 A.D.), very few sunspots were observed, which corresponded with the coldest part of the Little Ice Age (Dean, 2000). Previous research has shown a connect ion between solar variability and climate (Sonnett and Seuss, 1984; Schimmelmann et a l., 2003; Poore et al., 2004; Raspopov et al., 2008). Radioactive carbon is being continually produced fr om the bombardment of nitrogen with cosmic-ray produced neutrons, resulti ng in a form of carbon with an atomic weight of 14. The best known cycle of solar variabi lity is the eleven year sunspot cycle, known as the Schwabe Cycle. The number of dark blot ches (sunspots) on the sun’s surface cycles from a minimum to a maximum and then back to a minimum in eleven years (Dean, 2000). Sunspots are relatively dark ar eas on the surface of the sun where intense magnetic activity inhibits convection, resu lting in cooling of the surface. Increased solar activity (more sunspots) accompanie s an increase in the amount of “solar wind” from the sun, blocks cosmic rays that produce 14C from entering the atmosphere, and results in depleted 14C values. In contrast, decreased solar activity all ows in comic rays that produce 14C, resulting in enriched 14C values. Therefore, the 14C concentration of the atmosphere is lower during sunspot maxima an d higher during sunspot minima.

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14 1.4 The Holocene The Holocene encompasses the past 10,000 years of E arth’s history, and Greenland’s air temperature over this interval has been relatively stable as evidenced from Greenland ice core oxygen isotope records (All ey, 2000). Most of the knowledge of the late Holocene (2000-0 years BP) comes from hist orical records in addition to paleoclimate reconstructions (Keigwin, 1996; Winter et al., 2000; Watanabe et al., 2001; Goodkin et al., 2005; Richey et al., 2007). 1.4.1 The Little Ice Age and the Medieval Warm Peri od Abrupt climate events are defined as events where w idespread shifts in climate occur within a short period (decades) (Alley, 2004) Two abrupt climate events occurred over the Late Holocene, the Little Ice Age (LIA, 45 0-150 BP, Mann, 2002a) and the Medieval Warm Period (MWP, 1100-700 BP, Mann 2002b) Global and northern hemisphere climate records indicate that the end of the LIA was cooler than present day by about 0.5-0.7C (Hansen et al., 1996; Mann et al ., 1998). It has been proposed that the LIA may have been important in terms of increased v ariability of climate as opposed to changes in average climate (Mann, 2002a). The most dramatic climate extremes during this interval were less associated with multi-year periods of cold than with year to year temperature changes (Mann, 2002a). The cooling of t he LIA has frequently been blamed as the cause for the demise of the Norse settlement s in Greenland. Increased sea ice cover closed off previously accessible trade routes betwe en Scandinavia and Greenland, cutting off trade with mainland Europe, upon which the Nors e settlements relied (Mann, 2002a).

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15 The LIA followed the MWP, which was a period of war mer, moist climate that has recently received considerable attention due to the expected future of global warming (Cronin et al., 1999). Evidence of this interval ex ists by the presence of grapes suitable for making wine growing in England (Le Roy Ladurie, 1971). Also, evidence exists that the Scandinavian tree-line was 100-200 meters highe r than present (Karlen, 1998). These abrupt climate events have been reconstructed by numerous paleoclimate studies. For example, Keigwin (1996) examined oxyge n isotopes of the planktonic foraminifer Globigerinoides ruber (white) and found evidence of SST warming of ~1C during the Medieval Warm Period and cooling of ~1C during the Little Ice Age in the Sargasso Sea. Additional evidence comes from temper ature estimates of corals from Puerto Rico indicating 1-2C SST cooling during the Little Ice Age (Winter et al., 2000; Watanabe et al., 2001). Richey et al. (2007) examin ed Mg/Ca ratios of G. ruber (white) on marine sediments from the Pigmy Basin, Gulf of M exico and discovered that SST were warmer than present day during the Medieval Wa rm Period and ~2C cooler during the Little Ice Age. Haug et al. (2001) characterize d the Little Ice Age by three precipitation minima inferred from titanium concent rations in marine sediments from the Cariaco Basin. Currently, insufficient evidence exi sts as to whether these abrupt climate events were a global phenomenon or confined to the Northern Hemisphere. 1.5 Regional Setting 1.5.1 Pigmy Basin High resolution climate reconstruction can be recor ded in marine sediments which have high sedimentation rates, such as those found adjacent to deltas of rivers. High

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16 sedimentation rates result in excellent preservatio n of marine sediments and allows for accurate temporal reconstruction of terrestrial inp uts as well as sea surface conditions (Figure 5). Figure 5. Schematic of Mississippi River terrestria l input delivery to the Gulf of Mexico. Material enters the Gulf of Mexico and gets incorporated int o the sediments of the Pigmy Basin, along with marine algae and plankton. The Pigmy Basin, located in the northern Gulf of Me xico (2711.61 N, 9124.54 W), is ideally situated to record terrestrial input s entering the Gulf of Mexico from the Mississippi River due to its deep, open ocean setti ng and proximity to the mouth of the Mississippi River (Figure 6). Mississippi River Pigmy Basin, GOM Marine Sediments Algae

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17 Figure 6. Map of the United States with the Mississ ippi River Basin highlighted in purple. The location of the Pigmy Basin in the Gulf of Mexico a nd its proximity to the mouth of the Mississippi River is denoted. The Pigmy Basin is a blocked-canyon intraslope basi n approximately 20 kilometers by 7 kilometers in area (Bouma, 1983). T his oxic basin has its upper axis going from southwest to northeast, has a sill depth of ~1700m with the basin floor at ~2300m (Bouma et al., 1986), and contains hemipelag ic sediments (a mixture of pelagic and terrigeous sediment particles). Sedimentation r esults in the Pigmy Basin are extremely high (41cm/kyr), resulting in excellent p reservation of material and high resolution sampling. Marine sediments from the Pig my Basin have been utilized in several paleoclimate reconstructions during the Hol ocene (Richey et al., 2007) in addition to glacial/interglacial timescales (Deep Sea Drilli ng Project Hole 619, Jasper and Gagosian, 1989; Jasper and Hayes, 1990; Jasper and Gagosian, 1993). Laurentide Ice Sheet meltwater has also been documented in marine sediments from nearby Orca Basin Covers 41% of contiguous U.S. http://www.theodora.com/maps / Pigmy Basin

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18 (Kennett and Shackleton, 1975; Leventer et al., 198 2; Flower and Kennett, 1990; Flower et al., 2004; Hill et al., 2006) in addition to ear ly Holocene reconstructions (Brown and Kennett, 1999; LoDico et al., 2006). 1.5.2 Gulf of Mexico Climate The Gulf of Mexico is a low latitude semi-enclosed basin at the northwestern edge of the Atlantic Ocean. The sea surface tempera ture of the Gulf of Mexico reaches approximately 30C during the summer and 22C in th e winter. The Western Hemisphere Warm Pool (WHWP) forms entirely north of the equato r in the Eastern North Pacific during the Northern Hemisphere spring, and expands into the Caribbean and the Gulf of Mexico during the summer (Wang and Enfield, 2001). The WHWP is a monolithic heat source that migrates annually and changes in size ( Wang, 2002). Surface heat fluxes warm the WHWP during the boreal spring and sea surf ace temperatures and geographic extent of the WHWP reaches their maximums during bo real summer and early fall (Wang and Enfield, 2003). The moist air masses asso ciated with such high sea surface temperatures provide precipitation for areas in Nor th America that are drained by the Mississippi River. 1.6 Geochemical Approach 1.6.1 Field Site and Age Model During June 2003, a 57 centimeter box core (NPBC) w as taken from the Pigmy Basin on the R/V Longhorn Four-inch diameter subcores were taken from the b ox core and frozen for one year before sampling. The NPBC p rovided seven samples of a mixed

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19 assemblage of planktonic foraminifera from the >150 micron size fraction from various depths, which were dated using accelerator mass spe ctrometer radiocarbon dating at the Center for Accelerator Mass Spectrometry Lab at the Lawrence Livermore National Laboratory in Livermore, CA. Raw radiocarbon dates were converted to calendar years using the CALIB 5.0 program with a 400 year reservo ir correction (Stuiver et al., 1998; Appendix A). A linear relationship was determined b etween these seven calibrated ages and depths of the sediment core using a least-squar es regression (R2 = 0.996, Figure 7). It was determined that the core-top age was 0 years BP with a linear sedimentation rate of 43cm/kyr, thus the sediment core captured both mode rn and paleoceanographic conditions of the Gulf of Mexico. Foraminiferal da ta ( Globigerinoides ruber both pink and white varieties and Globigerinoides sacculifer ) from the NPBC core was compared with foraminiferal data from sub-core PB-BC1E, and dates were extrapolated using corresponding depths (Figures 21, 22 Appendix A). Figure 7. Age model constructed for core NPBC and p rojected onto sub-core PB-BC1E. Error bars are plotted for 1. A least squares regression gave an R2 value of 0.996. (Richey et al., 2007) R 2 =0.996

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20 The weight percent of insoluble residue is utilize d as a proxy for terrestrial input from the Mississippi River to the Gulf of Mexico. T he amount of discharge and the amount of suspended solids have been measured from the Mississippi River over the past 100 years, and are highly correlated on the seasona l cycle (Figure 8, Poore et al., 2001). Therefore, we infer increased loading to the Gulf o f Mexico as increased precipitation/wet events on the North American cont inent. Figure 8. Correlation between measured Mississippi River discharge rate and suspended solids (Poore et al., 2001). Titanium has been utilized in several studies as a proxy for terrestrial input to the ocean from the continent (Peterson et al., 2000; Ya rincik et al., 2000; Haug et al., 2001), Suspended Solids (tons/day) 0 5000 10000 15000 20000 25000 30000 35000 40000 0200040006000800010000120001400016000 y = -829.71 + 1.3977x R= 0.74955 MR discharge (Cubic feet/second)

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21 therefore we follow this previous work and infer in creases in titanium as increased precipitation/wet events on the North American cont inent, and not from African dust. High molecular weight n-alkanes are synthesized ex clusively in the leaf waxes of terrestrial plants (Eglinton and Hamilton, 1967). T herefore, their presence in marine sediments from Pigmy Basin results from delivery fr om the Mississippi River. Previous work has utilized the concentrations of high-molecu lar weight n-alkanes as an indicator of terrestrial input (i.e. Ohkouchi et, al., 1997). Hydrogen isotopes are a natural tracer for water a nd precipitation. Hydrogen isotopic composition of plant n-alkanes directly re flects that of the source water in which they were synthesized at the extent of evapotranspi ration. Several studies have utilized hydrogen isotopes on lipid biomarkers occurring in marine sediments as a proxy for hydrologic changes (i.e. Sauer et al., 2001; Hughen et al., 2004; Schefu et al., 2005). Compound specific hydrogen isotopic analysis of hig h-molecular weight n-alkanes synthesized in plant waxes provides insight into fu ndamental changes in the hydrologic cycle. We interpret them as indicators of hydrologi c conditions on the North American continent. 1.7 Thesis Organization This thesis is broken down into three chapters, tw o of which have been written as manuscripts to be submitted to peer-reviewed journa ls. Detailed methods are found in Chapter 2.

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22 In Chapter 3: Terrestrial Inputs to the Gulf of Me xico: Exploring Ocean-Continent Linkages During the Late Holocene Three terrestrial input proxies (weight % insolubl e residue, titanium abundance, and high-molecular weight n-alkane concentrations) are used to infer wet and dry intervals on the North American continent. These te rrestrial input records are compared with sea surface temperature and salinity records f rom Pigmy Basin to assess any ocean/continent linkages. The terrestrial input rec ords are also compared to a record of solar variability to examine any potential solar fo rcings. Solar variability and moisture flux from the Gulf of Mexico are invoked to explain the terrestrial input records to the Gulf of Mexico during the Late Holocene. Chapter 3 will be submitted to Geology In Chapter 4: Compound Specific D Analysis of High Molecular Weight N-alkanes as Indicators of North American Hydrologic Variability Hydrogen isotopic ratios of the high-molecular wei ght n-alkanes are used to document the hydrologic conditions within the Missi ssippi River drainage basin resulting from hydrologic variability. The D record is compared with the high molecular weight n-alkane concentration record. The influence of moisture flux from the Gulf of Mexico and solar variability is examined. C hapter 4 will be submitted to Geology or a similar journal. In Chapter 5: Complementary analyses of Pigmy Basin sediments A suite of inorganic and organic geochemical analy ses is used to document

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23 intervals of increased Mississippi River terrestria l input to the Gulf of Mexico and the subsequent biological response. These analyses incl ude the weight percent of total carbon, weight percent of total organic carbon, and the weight percent of calcium carbonate to look at fundamental compositional chan ges. Also grain size analysis, bulk density, and wet water content measurements examine some of the physical properties of the sediment. The carbon isotopic signature of b ulk total organic carbon, the isotopic signature of nitrogen, and the concentrations of lo w molecular weight n-alkanes will be discussed as biological productivity indicators. Th is chapter will not be published.

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24 Chapter 2 Research Methods 2.1 Field Site and Sediment Core The marine sediment core utilized in this research (PB-BC1E) was 57 centimeters in length and was taken to the Antarctic Marine Geo logy Research Facility at Florida State University to be split, scanned, and photogra phed (Figure 9). Smear slides of the core were taken every three centimeters to be analy zed with a microscope. In addition, a u-channel of the core was taken and sent to GFZ-Pot sdam to undergo XRF scanning. The split core was then taken into the laboratory and o ne-half of the core was extruded into 5 millimeter samples, obtaining a total of 115 sedime nt samples. This sampling interval of 0.5cm produced an average sample resolution of 12.3 years per sample. Each sample was then prepared for further analysis.

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25 Figure 9 Photograph of extruded half of sediment core PB-BC1 E. PB-BC1E is a sub-core of the NPBC boxcore taken on the R/V Longhorn in June, 200 3. 0cm 74 BP 57 cm 1492 BP

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26 2.2 Equations (1) Wet Volume of Sediment = (r2h) = ((5.08cm)2(0.5cm)) = 20.27cm3 (2) Wet Bulk Density = Mass Wet Sediment (g) Volume Wet Sediment (20.27cm3) (3) Dry Bulk Density = Mass Dry Sediment (g) Volume Wet Sediment (20.27cm3) (4) Wet Water Content (%) = (Mass Water (g) Mass Wet Sediment (g))*100 (5) Volume of Water (cm3) = Mass of Water (g) Density of Seawater (1.025 g/cm3) (6) Porosity (Void Ratio) (%) = ((Volume of Water ( cm3) Wet Volume of Sediment (cm3))*100 (7) Porosity (Void Ratio) (%) = (Wet Bulk Density ( g/cm3))*(Wet Water Content (%)) (8) Weight Percent CaCO3 = (Total Inorganic Carbon %)*(8.33) (9) Weight Percent Insoluble Residues = (100 – Weig ht % CaCO3 – Weight % TOC) (10) Period = 1/frequency 2.3 Grain Size Analysis Grain size analysis was performed on each sample a t the United States Geological Survey Center for Coastal and Watershed Studies in St. Petersburg, Florida on a Beckman 200 LS Series Coulter, which uses a system of multifunctional particle characterization tools. This instrument utilized la ser-based technology to analyze the sediment particles without missing the largest or t he smallest particles in a sample. The instrument technology is based on both the Fraunhof er and Mie theories of light scattering. The instrument uses reverse Fourier len s optics incorporated in a binocular lens system with a Fraunhofer optical module. Approximately one gram of wet sediment was added to a 100mL beaker with sodium hexametaphosphate buffer to break up the sed iment into individual particles. This

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27 sediment solution was then sonicated for one minute in a water bath to determine all of the grain sizes in the sample. This process was dup licated for each sample, and both graphs produced for each sample were overlapped to visually determine their agreement. If the curves did not agree, a third run was genera ted from the sample. The grain particle sizes were given geometrically in m (Udden-Wetworth grain size scale), and they were converted to the logarithmic phi ( ) scale using the equation = -log2(grain size diameter in mm)(Appendix A). 2.4 Physical Parameters Extruded samples were weighed to obtain the mass o f the wet sediment, dried for one week in an oven set at a temperature of 60C to ensure that no organics combusted, and then re-weighed to determine the dry mass of th e sediment and the mass of the water that was present in each sample (wet mass – dry mas s). The volume of sediment extruded for each sample was determined using the equation f or the volume of a cylinder, V = r2h, where r is the radius of the core and h is the h eight (Equation 1). Since the core had a 4 inch diameter, the radius was determined to be 5.08 centimeters, and the height was 0.5cm, since the core was extruded into 0.5 cm samp les. The volume was divided in half since only half of the extruded sub-core was utiliz ed in analysis. Therefore, the wet volume of each sample was determined to be 20.27cm3. Bulk wet density was determined for each sample by dividing the mass of the wet sed iment by the volume of sediment extruded (Equation 2) (Bouma et al., 1986; Stephen s et al., 1992). Dry bulk density was determined by dividing the mass of dry sediment by the volume of wet sediment (Equation 3) (Stephens et al., 1992; Mingram et a l., 2004). The wet water content was

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28 determined by dividing the mass of water in the sed iment by the mass of wet sediment (Equation 4) (Bryant et al., 1986). Porosity (voi d ratio) of each sample was determined two ways according to the literature; dividing the volume of the water (determined using the density of water as 1.025g/cm3 and the mass of the water (Equation 5)) by the vol ume of wet sediment (Equation 6) (Bouma et al., 1986), and also by multiplying the wet bulk density by the wet water content (Equation 7) (Boyc e, 1976; Appendix A). 2.5 Carbon Concentrations Sediment samples were analyzed for total carbon con centration and inorganic carbon concentration at the College of Marine Scien ce, University of South Florida using a CM5104 UIC Carbon Coulometer, which measures carb on in any carbon dioxide (CO2) containing gas. A stream of CO2 gases passes into a cell filled with a solution co ntaining monoetholomine and a colorimetric pH indicator. Pla tinum (cathode) and silver (anode) electrodes are positioned inside the cell, which is then placed inside the coulometer compartment between a light source and a photodetec tor. As a stream of gas containing CO2 enters the cell, the CO2 is quantitatively absorbed, and reacts with the monoetholomine to form a titratable acid. This acid causes the color indicator to fade, which is monitored as percent transmittance. As per cent transmittance increases, the titration current is activated and measured continu ously until all of the acid has been titrated, and converted to a carbon percentage. Thi s is based on the principles of Faraday’s Law, which states that one faraday of ele ctricity will result in the alteration of one gram equivalent weight of a substance during el ectrolosis. In this case, each faraday of electricity expanded is equivalent to one gram e quivalent weight of CO2.

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29 2.5.1 Combustion – Wt % TC To determine the total carbon concentration of ea ch sample, blank samples were run first on the combustion side of the coulometer to ensure that the results obtained contained no background carbon. To standardize the samples, three samples of calcium carbonate were weighed (milligrams), placed into a porcelain boat, and then placed into the coulometer combustion oven. A standard curve wa s created from the three standard samples to calibrate the instrument based on the co rrelation coefficient (r2). A known quantity of each sediment sample (approximately 40 milligrams) was weighed out and placed in a porcelain boat into the carbon coulomet er oven, which combusted the sample at 970C in the presence of excess oxygen. All of t he carbon was oxidized into carbon dioxide to determine the total carbon concentration A standard was run every ten samples to ensure accurate results. 2.5.2 Acidification – Wt % CaCO3 Once the total carbon concentration had been determ ined for each sample, all samples were run on the acidification module of the carbon coulometer to determine inorganic carbon concentrations. Again, blank sampl es were run first on the acidification side of the coulometer to ensure that the results o btained contained no background carbon. Three standard samples of calcium carbonate (approximately 15 milligrams) were weighed out and placed into a glass sample fla sk, which were then acidified using 5mL of 2 M phosphoric acid. A standard curve was cr eated using the standard samples, again to ensure accuracy of the instrument based on the correlation coefficient. A known quantity of each sediment sample was weighed out an d placed into a glass sample flask,

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30 then acidified in a heated reaction vessel to measu re all forms of inorganic carbon (including dissolved carbon dioxide, carbonate ions bicarbonate ions, and carbonic acid) using 2M phosphoric acid. A carbon dioxide-free car rier gas pushes the reaction products through a scrubbing system and into the coulometer for detection. 2.5.3 Wt % TOC and Wt % Insoluble Residue Total carbon concentrations and inorganic carbon co ncentrations were determined using the standard curve equations created from the standard calcium carbonate samples and the carbon counts determined by the coulometer. To obtain the total weight of the carbon in the sample, the carbon counts generated b y the oven part of the coulometer were entered into the equation generated by the sta ndard curve. The total weight of the carbon in the sample was then divided by the total weight of the sample and multiplied by one-hundred to obtain the percent of total carbon i n the sample (Appendix A). To obtain the total weight of inorganic carbon in the sample, the carbon counts from the acidification part of the coulometer were entered i nto the equation generated by the standard curve. The weight of the inorganic carbon in the sample was then divided by the total weight of the sample and multiplied by one-hu ndred to obtain the percent of inorganic carbon in the sample (Appendix A). Once t he total carbon concentrations and inorganic carbon concentrations had been determined for each sample, the inorganic carbon concentrations were subtracted from the tota l carbon concentrations to determine the organic carbon concentrations (Appendix B). Cal cium carbonate concentrations were determined by dividing the inorganic carbon counts by the total weight of the sediment sample, and multiplying by 8.33 (Equation 8; Append ix A). The weight percent of

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31 insoluble residues were calculated using the equati on 100-%TOC-%CaCO3 (Equation 9; Appendix A). 2.6 Bulk Carbon and Nitrogen Isotopes In order to calculate the bulk organic carbon and n itrogen isotopes in the samples, a subsample (~0.5g) of dried sediment was placed in a 500 mL beaker. The beaker was filled halfway with 0.1N hydrochloric acid (HCl) to acidify and remove all the carbonates (in order to get isotope analysis on only the organ ic material of the sediment). Evidence of bubbles/effervescence in the beaker indicated th at the carbonates were reacting with the acid and converted to CO2 gas. When all the carbonates had been removed, th e acid was decanted off and the sediment was rinsed with M illi-Q water, which was also decanted off. This was repeated two more times to e nsure that all of the acid had been removed. The sample was placed in an oven set at 65C (low e nough so that the organics would not combust) to dry. After the sediment had dried, the beakers were removed from the oven and the sediment was ground very finely wi th a clean mortar and pestle. Each sample was then placed into a tin capsule and analyzed at the College of Marine Science, University of South Florida on a Th ermo Finnigan Delta Plus XL Continuous Flow Isotope Ratio Mass Spectrometer int erfaced with a Carlo Erba NA 2500 Series Elemental Auto Analyzer to obtain the bulk i sotopic values of organic carbon and nitrogen in the samples. The tin capsules were load ed into an autosampler carousel and entered the EA through a combustion tube kept at 10 00C and constantly crossed with a helium stream, which combusted the sample and conve rted all of the carbon into CO2, all nitrogen into various forms of NOx, and produced wa ter as a byproduct. These gases then

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32 entered an oxidative catalyst layer (Cr2O3) in the lower portion of the tube where oxidation was completed, and then entered a reducti on reactor kept at 780C and contained copper, which reduced the gases to CO2 and N2 (water was also still present). From the reduction reactor, the gases entered a wat er trap, which trapped all of the water present, and entered a gas chromatographic column t o separate all of the gases. They then entered a ConFloII, which is where the reference ga ses were injected into the instrument along with the sample gases. A helium dilutor was a lso added here to dilute the carbon portion of the sample in order to read the carbon i sotopes on the same range as the nitrogen isotopes, because carbon is much more abun dant that nitrogen in the samples. The carbon isotopes were standardized to ‰ Pee Dee Belemnite (PDB) and calibrated with NIST-1570a (spinach leaves) and the nitrogen i sotopes were standardized to ‰ Air (Appendix C). 2.7 Titanium The elemental composition (including titanium) of the core was determined using X-Ray Fluorescence (XRF) Scanning Technologies at G FZ-Potsdam. The scanner (EAGLE III BKA; Rntgenanalytik Messtechnik GmbH) s canned a u-channel of sediment core PB-BC1E at 500 m resolution with a spot size of 400 m by obtaining point measurements (Appendix A).

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33 2.8 Molecular Organic Geochemistry Lipid analysis was performed at the College of Mari ne Science, University of South Florida using a modified procedure from S.G W akeham and T.K. Pease at the Skidaway Institute of Oceanography (unpublished man uscript, 1992). 2.8.1 Glassware Washing and Solvent Rinsing All glassware (except the long-columns) was first washed with tap water (if necessary) and then rinsed with DI or Milli-Q water Once dry, each piece of glassware was rinsed with ACS grade Methanol, ACS grade methy lene chloride (DCM), Optima grade methanol, and finally Optima grade DCM. A pie ce of aluminum foil was placed on top of each piece of glassware, and all glassware w as then fired in an annealing oven for at least two hours at 425C in order to combust any organic material remaining in the glassware. Once the glassware had cooled, it was re ady to use again. The columns underwent a different cleaning procedu re because they were too long to fit into the annealing oven. Each column ha d the contents removed by placing the end of the nitrogen blowdown hose over the end of t he column and holding it upside down over a trash can. The stream of nitrogen gas f orced the contents of the column into the trash can. The columns were then rinsed followi ng the aforementioned procedure. After the Optima DCM rinse, the columns underwent a rinse with Optima hexane. The columns were then placed back into their ring holde rs and another 20 mL of hexane were flushed through the columns to remove any remaining organic material in the columns. All solvent waste were collected in an appropriate container and disposed of accordingly.

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34 2.8.2 Silica and Alumina Gel Extraction and Deactiv ation Silica-gel and alumina adsorption were extracted u sing the lab procedure described next. Upon extraction, they were placed i n an annealing oven at 125C to activate them (i.e. remove all hydration). They wer e then deactivated to 5% water to make each solid adsorbant phase not as active (sili ca: 5mL of DI water per 100g; alumina 2.5 mL of DI water per 50g). 2.8.3 Soxhlet Extraction of Samples – Total Lipid E xtraction Cellulose thimbles were pre-extracted with a 2:1 m ethylene chloride/methanol solvent and air-dried in a fume hood. A known quant ity of each dried sediment sample was placed into a cellulose thimble, and the thimbl e was placed into a solvent-rinsed and fired glass Soxhlet-extractor. A solvent-rinsed fla sk containing pre-extracted boiling chips was attached to the extractor, and 400 mL of 2:1 methylene chloride/methanol solvent was poured into the extractor onto the thim ble, and drained into the flask. A mixed solution of DCM and methanol was used because each solvent had a different polarity (methanol is more polar than DCM), and the refore the mixture is capable of extracting both polar and non-polar compounds very efficiently. The round-bottom flask/condenser was placed onto a heating unit and attached to a condenser containing a 1:1 solution of water and anti-freeze (bought pre-d iluted). Soxhlet-extraction works because the organic solvents boil and the vapors tr avel up the apparatus, where they encounter the circulating anti-freeze and condense, falling back toward the samples. As this process repeats, the organic material in the s ediment is extracted. Each sample was

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35 extracted on the hotplates for twenty-four hours to ensure that all of the organic matter had been extracted. When the samples were extracted and cooled, the sol vent present in the roundbottom flask was poured into a 1000 mL separatory f unnel. The round-bottom flask was then rinsed with the 2:1 methylene chloride/methano l solvent to remove any remaining extracted solvent and added to the separatory funne l. A 5% aqueous sodium chloride solution (made by adding 50 grams of NaCl to a flas k and then adding 950mL of Milli-Q water) was added to the separatory funnel to wash t he extracted samples and form a twophase (water-methanol/organic) system. The funnel w as capped, inverted, and shaken about thirty times, pausing to open the stopcock an d release any pressure build-up. The organic phase on the bottom was drained into a new, solvent-rinsed round-bottom flask. The separatory funnel was rinsed with methylene chl oride, capped, shaken, and the organic layer was again drained into the same round -bottom flask. This was repeated a third time, and the aqueous layer remaining in the separatory funnel was then discarded. The organic layer in the round bottom flask was add ed to the empty separatory funnel, and 5% sodium chloride solution equivalent to 1/3 o f the volume of the organic liquid was added to the separatory funnel. The separatory funnel was shaken, and the phases were allowed to separate. The organic phase was the n drained into a clean, solvent-rinsed round-bottom flask, and anhydrous Na2SO4 was added to remove any water remaining in the organic phase. The organic phase was allowed to sit overnight. The round-bottom flask was then placed on a rotary evaporator and excess solvent was evaporated off in a water bath of 30C to ensur e that all of the volatile organic compounds remained in the flask and were not boiled off. Once the solvent remaining in

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36 the round-bottom flask got to a low volume, the sol vent was transferred into a pearshaped flask using a clean, solvent-rinsed disposab le pipette and brought to near dryness. The pear-shaped flask was then rinsed with methylen e chloride and evaporated on the rotary evaporator to near dryness again. This was r epeated three times, and the remaining solvent was transferred using a clean, solvent-rins ed disposable pipette into an “ashed” (annealed for two hours at 425C) vial with a Teflo n lined cap and labeled “total lipid extract,” which was then brought to dryness using n itrogen gas. 2.8.4 Separation of Compound Classes Total lipid extracts were separated into compound c lasses using long-column chromatography. Silica-gel and alumina adsorbants w ere Soxhlet extracted to remove any organics via the aforementioned procedure and dried in a hood for 6 hours on aluminum foil. The extracted silica-gel and alumina adsorban ts were then placed in an oven at 125C for 24 hours to activate it. They were then c ooled and placed into glass jars and deactivated by adding 5% of its weight of deionized water (5mL per 100g) using a solvent-rinsed disposable pipette. Alumina is much more active than silica gel and adsorbs much more strongly. It also may react with double bonds that may occur in organic compounds and cause either isomerization or migration. Deactivating the alumina maintains the active sites on the solid ads orbant phases but prevents interaction with double bonds of organic compounds. This is not much of a problem for hydrocarbons, but could potentially be a problem fo r more polar compounds. The alumina is also useful for cleaning up the sample a nd prevents the sample from overloading the silica, thus resulting in better se paration. As compounds get eluted down

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37 the column, the polar compounds remain on the alumi na, also resulting in better separation. Each column was dry-packed with silica-gel and alum ina adsorbant. A sample of 7 grams of 5% deactivated silica was placed into a solvent-rinsed long column (9 mm x 300 mm with a 250 mL bulb) which was then tapped wi th a pencil to ensure that the silica was tightly packed in the column. A sample o f 2 grams of 5% deactivated alumina was also weighed and placed on top of the 7 grams o f silica, and again the column was tapped with a pencil. A small piece of glass wool w as then placed on top of the 2 grams of alumina to catch the TLE as it was loaded into t he column and to prevent the alumina from “flying” into the solvent.. A sample of 30 mL of hexane was added to the column to remove any remaining organics before adding the sam ple. Total lipid extracts were brought to dryness using nitrogen gas and re-dissolved with 250 uL of methylene chloride. Each sample was then loaded into the column via a solvent-rinsed disposable pipette, and 30 mL of hex ane were added to drip through the column to collect the L1/L2 fraction containing n-alkanes. This fraction was co llected in a solvent-rinsed and ashed 50 mL pear-shaped flask. T he A-L4B fraction containing longchain alkenones was collected into a solvent-rinsed and ashed 100 mL pear-shaped flask by adding 20 mL of 25% toluene/75% hexane, 50% tolu ene/50% hexane, 5% ethyl acetate/ 95% hexane, and 10% ethyl acetate/90% hexa ne solvents, respectively. When this fraction was being rotary evaporated to near d ryness, and azeotrope was formed by adding 1/3 of the volume of methanol. A mixture of methanol/toluene has a much lower boiling point than that of pure toluene, and theref ore the rotary evaporator could remain at a low temperature. The L5-L6 fraction containing sterols and stenones was collec ted

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38 into a solvent-rinsed and ashed 50 mL pear-shaped f lask by adding 20 mL of 15% ethyl acetate/85% hexane and 20% ethyl acetate/80% hexane The L7-L10 fraction containing other polar molecules was collected into a solventrinsed and ashed 250 mL roundbottom flask by adding 25% ethyl acetate/75% hexane 100% ethyl acetate, and 100 % methanol solvents. The solvents were added in order of their polarity, beginning with non-polar hexane, which is a saturated alkane. Each fraction was then rotary evaporated to near dr yness, re-dissolved with hexane, brought to near dryness again, and then pla ced into an ashed 2 mL vial with a Teflon cap using a solvent-rinsed disposable pipett e. The A-L4B, L5/L6, and L7/L10 fractions were then placed in a freezer for storage for they were not analyzed. The L1/L2, fractions were brought to dryness using nitrogen ga s and underwent further procedures. 2.8.5 Separation of Urea Adducts and Non-Adducts on L1/L2 Fraction Each L1/L2 fraction underwent urea adduction to separate cycl ic and branched alkanes from normal alkanes. 200 L of 10% urea in methanol (made by adding 10 grams of urea to a flask and adding 900 mL of methanol), acetone, and pentane were added to the vial. The vial was then capped, shaken, and pla ced in a -4C freezer for 30 minutes. After 30 minutes, the excess solvents were evaporat ed using nitrogen gas. The remaining crystals were washed three times with hexane, and t he wash solvents containing nonadductable branched and cyclic alkanes was placed i nto a 2 mL vial labeled “nonadducts” using a 250 L syringe. The remaining urea crystals containing t he adductable normal and isoalkanes were then dissolved in 500 L of methanol and 500 L of deionized water. The adductable hydrocarbons were e xtracted three times with hexane,

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39 and the hexane fractions were placed in a 2 mL vial labeled “adducts.” This vial was then brought to dryness using nitrogen gas, and the proc edure was repeated two more times to remove any remaining non-adducts. The final “adduct s” were placed directly into a 50 L autosampler glass insert and placed into a 2 mL aut osampler glass vial, and brought to dryness using nitrogen gas. 2.9 Gas Chromatography Quantification of compounds was performed on a Hewl ett-Packard 5890 Series II gas chromatograph with a flame ionization detector (GC-FID) on a fused silica Alltech AT™-5 non-polar column (the stationary phase contai ning 95% methyl groups and 5% phenyl groups). The column length was 30m, the inte rnal diameter was 0.25mm, and the film thickness was 0.25 m. The oven temperature on the GC was set at 50C ( lower than the boiling point of the compounds), the injection temperature was set at 250C, and the detector temperature was set at 250C. The injectio ns were splitless (all molecules were “trapped” at the head of the column) and there was a constant flow of hydrogen as the carrier gas (mobile phase) at 18psi. A column compe nsation run was performed by not injecting any sample and was subtracted from the ru n of each sample. This was done to compensate for any column bleed, which is the norma l background signal that occurs from some portion of the stationary phase being deg raded. 2.9.1 L1/L2 Fraction Each L1/L2 fraction containing the n-alkanes was brought to dr yness using nitrogen gas and re-dissolved with 25 uL of hexane, and 2 uL of each sample was

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40 injected via an autosampler into the GC using a 10 uL syringe. The compounds were injected at 250C with an initial temperature hold of 50C for two minutes, followed by a temperature ramp of 8C/min, with an isothermal hol d at 310C for 26 minutes. The compounds were detected by a flame ionization detec tor (FID) at 250C and identified by comparison with a C13-C34 n-alkane standard created at USF based on retentio n time (the amount of time between the start of the run and whe re the peak comes out) of the compounds. Ten standard samples of 5-alpha-androsta ne were run to determine the area under the curve for a known concentration. A relati onship was determined between the area of each compound and its concentration of orga nic matter assuming that concentrations are proportional to chromatogram pea k area and that the response factor is the same for 5androstane (Appendix B). 2.10 Deuterium Analysis The L1/L2 fraction containing the straight chain n-alkanes w ere analyzed for deuterium isotopes on a Thermo Finnigan Delta Plus XL Continuous Flow Mass Spectrometer interfaced with an Agilent 6890 Gas Ch romatograph with a fused silica Durabond DB-5 non-polar column. The column length w as 30m, the internal diameter was 0.25mm, and the film thickness was 0.25 m. An H3 factor was run prior to injecting any samples. Approximately 2 L of each sample was injected via an autosampler in to the GC using a 10 uL syringe. The compounds were inject ed at 250C with an initial temperature hold of 70C for six minutes, followed by a temperature ramp of 5C/min, with an isothermal hold at 300C for 8 minutes. Upo n exiting the gas chromatograph the compounds entered the pyrolosis reactor that was se t at a temperature of 1450C. There

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41 the sample was converted to a gaseous state and int roduced into the mass spectrometer. The compounds were identified by comparison with th e Indiana Mix A standard based on retention time of the compounds, and standardized t o ‰ Standard Mean Ocean Water (SMOW). A drift correction as applied to each run b ased on the 3rd reference gas (Hydrogen) peak at the beginning of the run and the 1st reference gas peak at the end of the run (Appendix C). 2.11 Time Series Analysis Time series analysis was performed on the various proxies using the AnalySeries program. The program resampled the data at 12.3 yea rs before performing any statistical analysis to establish the time step. Each proxy was then subjected to a basic math periodogram analysis which measured the spectral fr equency (f), from which cycles can be determined at the 95 % confidence level. The cyc les were converted to years using the equation = 1/frequency (Equation 10).

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42 Chapter 3 Terrestrial Inputs to the Gulf of Mexico: Exploring Ocean-Continent Linkages During the Late Holocene 3.1 Pigmy Basin terrestrial input records 3.1.1 Insoluble Residue The weight percent (wt %) of insoluble residue is i ndicative of terrestrial, nonorganic lithogenic material derived from the contin ental USA and delivered to the Gulf of Mexico via Mississippi River discharge. Suspended s olids increase with measured flow of the Mississippi River (Poore et al., 2001). Ther efore we infer that increased concentrations of terrestrially derived lithic mate rial reflect periods of increased discharge associated with wet intervals on the cont inental USA. The weight percent insoluble residue record shows e pisodes of significantly increased terrestrial inputs and subsequent enhance d Mississippi River discharge (wet intervals) centered at ~450 and ~1200 BP (Figure 10 -C), which is at the onset of the Little Ice Age (LIA, 450-150 BP, Crowley and Lowery 2000) and before the onset of the Medieval Warm Period (MWP, 1100-700 BP, Mann, 2002b ). These inputs peaked at 86.6 and 89.2 wt % insoluble residues, respectively (Fig ure 10-C). Episodes of decreased terrestrial input from the continental USA at ~150, ~850, and ~1400 BP., are interpreted as dry conditions in the Mississippi River basin an d occur after the LIA, during the

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43 MWP, and before the MWP, respectively, with lows of ~78, ~78.2, and ~79.2 wt % insoluble residues (Figure 10-C).

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44 Terrestrial Input Salinity SST MWP LIA (A) (B) (C) (D) (E) Dry Wet

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45 Figure 10. Records of terrestrial input from the co ntinental USA to the Gulf of Mexico via Mississippi River discharge plotted versus age (yea rs BP). Each record shows two maxima (wet intervals) at 450 and 1200 BP, respectively, and th ree minima (dry intervals) at 150, 850, and 1400 BP. Records of Gulf of Mexico climatology are also plotted with terrestrial input records. Shaded areas indicate intervals of good agreement, red representing dry conditions on the North American continent and blue representing wet condit ions on the North American continent. The LIA and the MWP are indicated with arrows. A. HMW n -alkane C25 and C27 concentrations. B. Titanium (in counts per second) C. Weight percent i nsoluble residue D. Salinity reconstruction from the Pigmy Basin determined from paired analysi s of Mg/Ca and 18O and G. ruber (Richey et al., 2007). E. SST reconstruction from the Pigm y Basin determined from Mg/Ca ratios on G. ruber (Richey et al., 2007). Each curve was smoothed usi ng a 3-pt running mean and plotted with the raw data. 3.1.2 Titanium Titanium is interpreted as a terrestrially derived element delivered to the ocean via terrestrial watersheds (Peterson et al., 2000; Hast enrath and Greishar, 1993). Titanium has been used in the Cariaco Basin as a proxy for c hanges in terrigenous sediment input. Therefore we infer its presence in marine sediments from the Pigmy Basin to be delivered from the continental USA via Mississippi River disc harge. The titanium record shows episodic increases at ~450 and ~1200 BP, with peaks of ~60.7and ~65.6 counts per second (cps), respectively, further supporting the notion of wet conditions over the continental USA during these intervals (Figure 10-B ). The titanium record also shows decreases at ~150, ~850 and ~1400 BP, with cps lows of ~33.8, ~38.7, and ~37.3, respectively, further suggesting dry conditions ove r the continental USA. When the insoluble residue record is cross-correlated with t he titanium record, extremely strong correspondence is observed (r = 0.66, Figure 10-B), suggesting that these two independent proxies are accurate recorders of Missi ssippi River terrestrial input to the Gulf of Mexico.

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46 3.1.3 HMW n-alkanes Organic lipid biomarker compounds can provide a tra cer for the sources of sedimentary organic matter. Organic compounds produ ced by terrestrial plants have been identified in marine sediments as long-chain high m olecular weight (HMW) n-alkanes (C25-C33) with odd carbon number predominance, which are sy nthesized in epicuticular waxes in higher plants (Eglinton and Hamilton, 1967 ; Pancost and Boot, 2004). HMW nalkanes are an excellent proxy for terrestrial inpu ts because they are relatively resistant to degradation, and assessment of HMW/LMW n-alkane rat ios gives confidence that the nalkanes in this study have minimal diagenetic alter ation and are a viable source of terrestrial inputs. The Pigmy Basin HMW n-alkane record agrees with the previously discussed records of terrestrial inputs from the Mississippi River into the Gulf of Mexico. The concentration of each n-alkane was normalized to pe rcent organic carbon to obtain a concentration in micrograms/gram and to ensure that observed variations were indeed due to varying terrestrial input and not from the d ilution of their marine counterparts. Two representative n-alkane concentrations (C25 and C27) also show increased intervals at ~450 and ~1200 BP (Figure 10-A) and decreased input s at ~150, ~850, and ~1400 BP. Concentrations peak at ~15000 and ~15760 g/g, respectively, and have lows of ~1343, 2154, and 1533 g/g, respectively (Figure 10-A).

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47 3.2 Linking Mississippi River terrestrial input to Gulf of Mexico changes 3.2.1 Wet Intervals Since the Gulf of Mexico is the primary source of m oisture to the continental USA (Hirschboeck, 1991), we hypothesize that the mo isture balance between the continent and the Gulf of Mexico is directly depend ent on the evaporative conditions (E/P) in the Gulf of Mexico. To further examine thi s, we compared our terrestrial input records with a sea-surface temperature (SST) record from the Pigmy Basin determined from the ratio of Mg/Ca (Figure 10-E), and an inter preted salinity record produced from paired analysis of Mg/Ca and 18O on the planktonic foraminifer Globigerinoides ruber (Richey et al., 2007, Figure 10-D). These two recor ds are from the same box-core and have the same age control as the records discussed in this study. No cross-correlation (r = 0.1) exists between the Mg/Ca SST record and the in soluble residue record, therefore Mississippi River discharge into the Gulf of Mexico is not driven by Gulf of Mexico temperature variations. Conversely, there is a larg er cross-correlation between the insoluble residue record and the salinity record fr om Pigmy Basin (r = 0.4, Figure 10C,D). This correlation suggests that large scale E/ P variations in the Gulf of Mexico are directly related to Mississippi River discharge inf erred by the terrestrial input records. Since high salinity intervals correspond with inter vals of increased terrigenous input from the Mississippi River into the Gulf of M exico (Figure 10), our proposed mechanism driving hydrologic variability suggests t hat moisture evaporated seasonally from the Gulf of Mexico migrates meridionally over the continental USA. For instance, during boreal summer, intensified atmospheric circu lation, in conjunction with a westward, well-defined Bermuda High, enhance meridi onal moisture flux from the Gulf

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48 of Mexico. The warm, moist air masses from the Gulf of Mexico travel northward over the continental USA via the Great Plains Low Level Jet where they fall as precipitation due to convective processes (thunderstorms and trop ical cyclones) as well as convergent processes that occur when the warm, moist tropical air masses meet the cold, dry air coming from the north (Arctic region) and northwest (Pacific Ocean) (Hirschboeck, 1991) and condense. Any precipitation falling withi n the Mississippi River basin returns to the Gulf of Mexico via Mississippi River dischar ge, but the resulting increase in freshwater is confined to coastal areas of the Gulf of Mexico whereas sediment and “lithic” material (fine grained clays and soil orga nic matter) is transported off-shore and deposited at intraslope basins, such as the Pigmy B asin (Goni et al., 1997). Therefore, enhanced Mississippi River discharge does not affec t the salinity in the Pigmy Basin, and salinity is an accurate recorder of E-P. Examining the influence of winter storms/precipitat ion in the Mississippi River basin on Mississippi River discharge is also import ant, because snow pack and ice melting contributes to enhanced Mississippi River d ischarge. Most boreal winter storms in the Mississippi River basin occur when moist air from the Gulf of Mexico converges with extremely cold, dry air from the arctic in the western Great Plains region (www.weather.com). The storms then migrate east and northeast, providing snow and ice for the Mississippi River basin, which melt and con tribute to Mississippi River terrestrial input. During this time, atmospheric circulation ov er the Gulf of Mexico is weakened, and the Bermuda High remains east and undefined, ho wever Gulf of Mexico moisture flux is sufficient enough to interact with the cold dry air masses to cause storms.

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49 3.2.2 Dry Intervals During the inferred dry intervals on the North Ame rican continent, Gulf of Mexico salinity is low, indicating a decrease in th e ratio of E/P over the Gulf of Mexico. It has been hypothesized that drought occurring in the Great Plains during these times, especially at 850 BP, is due to an intensification of westerly flow patterns (zonal flow) which causes an increase in the duration of dry air masses from the Pacific, which block moisture from the Gulf of Mexico entering the Missi ssippi River basin region (Bryson and Baerreis, 1968; Bryson et al, 1970; Booth et al ., 2006; Shinker et al., 2006). The reduced Gulf of Mexico meridional moisture flux ove r the North America continent results in reduced duration and/or frequency of war m, moist air masses over the continental USA, causing dry conditions to prevail. At the present time, the temporal resolution of th ese records is not sufficient to capture the seasonality of these dry events, theref ore we do not know if these wet intervals and dry intervals were more of a summer o r winter precipitation or drought signal. However, warm season droughts may have dry conditions that continue due to recurrent subsidence of air (sinking air) (Namias, 1983). This may lead to heat waves, no cloud development, and soil moisture deficits (Nami as, 1983) that would also affect the moisture balance in the Mississippi River. In contr ast, cold season droughts are associated with cyclonic atmospheric wind patterns and sea surface temperature anomalies in the North Pacific (Namias, 1983). The conditions that accompany warm or cold season droughts may explain some of the discon nect observed in the comparison of the Pigmy Basin terrestrial input records and salin ity record, especially when there is low terrestrial input and high salinity.

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50 There is a variety of paleoclimatic data available from the Mississippi River basin that provides insight into the hydrologic variabili ty of this region throughout the Late Holocene. Several other terrestrial records of hydr ologic variability also show episodes of drought in the Mississippi River basin during the i nferred dry conditions in the records produced in this study at 850 BP. A diatom-inferred salinity record from Moon Lake in North Dakota (Laird et al., 1996) shows a high sali nity peak centered at ~850 BP that corresponds with the dry interval in these records. Miao et al. (2007) report a long chronological record of dune fields and loess depos its from the Great Plains that imply an interval of drought from 1.0-0.7 ka BP from a maxim um episode of eolian activity, also coinciding with the dry interval observed in the re cords discussed in this paper. There are several other records that report dry conditions an d/or drought in the central United States/ Great Plains region (Mississippi River drai nage basin) between ~1000 and ~800 BP using various proxies such as sand dune activity in the Nebraska Sandhills (Stokes and Swinehart, 1997; Mason et al., 2004; Sridhar et al., 2006), lacustrine salinity reconstructions from Cold Water Lake and Rice Lake, North Dakota (Fritz et al., 2000), tree-ring reconstructions (Cook et al., 2004), allu vial records from Southwest Nebraska (Daniels and Knox, 2005), stalagmites from Devil’s Icebox Cave, central Missouri (Denniston et al., 2007), and increased aeolian-der ived materials in the sediments of Elk Lake, north-central Minnesota (Dean, 1997). The dry interval at 150 BP in these records has been documented as a “Civil War” Drought and dr y conditions were reported in Kansas newspapers (Bark, 1978). Early explorers rep orted blowing sand and dune reactivation during this time interval in the Great Plains (Muhs and Holliday, 1995).

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51 Additional moisture balance evidence in the Gulf of Mexico region during these time intervals comes from 18O records on ostracods and gastropods from Lake Pun ta Laguna on the Yucatan Peninsula, Mexico, in the sub tropics (Hodell et al., 2007). High lake levels indicative of wetter times were inferre d from low oxygen isotope values beginning at 1000 A.D., roughly corresponding with the decreased salinity in the Gulf of Mexico salinity record and dry interval observed in the terrestrial input records at 850 BP. This further suggests that the Gulf of Mexico w as not a highly evaporative region at 850 BP and moisture flux from the Gulf of Mexico to the continental USA was reduced, resulting in dry conditions. 3.3 Periodic Variability Spectral time series analysis was performed on the insoluble residue data using the periodogram technique on AnalySeries. The resul ts show significant (at the 95% confidence level) powers at ~200 years and ~70 year s, which we attribute to solar forcing and the Atlantic Multidecadal Oscillation, respecti vely. Evidence exists of a 200 year cycle of sunspot activity known as the Suess cycle or the de Vries cycle (Raspopov et al., 2008). It has been suggested that this 200 year sol ar cycle is a dominant cycle during the Holocene (Vasil’ev et al., 1999). Vegetation assimilates both 12C and 14C before it decays, therefore the ratio of 12C and 14C provides insight into the amount of available 14C present in the atmosphere. This provides an important marker for solar variability. The century scale oscillations manifested in the insoluble residue record are simi lar to the oscillations observed in a 14C record produced from tree-ring studies and used a s a proxy for solar variability

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52 because the trees are going to assimilate carbon di rectly from the atmosphere into the wood (Stuiver, 1998, Figure 11-D). Previous paleocl imate studies have invoked solar variability as a mechanism for climate variability (Verschuren et al. 2000; Hodell et al. 2001; Poore et al., 2004). Figure 11. Comparison of the A. Gulf of Mexico SST record (Richey et al., 2007). B. Gulf of Mexico salinity record (Richey et, al., 2007). C. W eight percent insoluble residue terrestrial input record. D. 14C solar variability record (Stuiver et al., 1998) w ith the solar minimums denoted. Each record is plotted versus age (years BP). Shade d areas indicate intervals of good agreement, Terrestrial Input Solar Activity Maunder Minimum Sporer Minimum Wolf Minimum Oort Minimum Medieval Maximum MWP LIA Salinity SST (A) (B) (C) (D) Dry Wet

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53 red representing dry conditions on the North Americ an continent and blue representing wet conditions on the North American continent. More de pleted 14C values are indicative of increased solar activity. Blue arrow indicates terrestrial i nput to the Gulf of Mexico, and yellow arrow indicates increasing solar activity. The LIA and th e MWP are indicated with arrows. The weight percent insoluble residue record, Gulf o f Mexico salinity record, and 14C solar variability record agree with one another extremely well (Figu re 11-B,C,D), suggesting a solar forcing mechanism behind wet and dry events in the Mississippi River basin. For instance, the interval of low terrestria l input to the Gulf of Mexico inferred as dry conditions on the North American continent at 8 50 BP coincides with the Medieval Maximum, when 14C values are depleted, indicative of increased sola r activity. Intervals of increased terrestrial input to the Gulf of Mexic o coincide with the Oort, Wolf, Sporer, and Maunder Minimums when the 14C values are relatively enriched, suggesting decreased solar variability leading to wet conditio ns on the North American continent. Therefore, solar variability must be driving the at mospheric circulation patterns that result in wet and dry events on the North American continent. The Atlantic Multidecadal Oscillation (AMO) is an index of sea surface temperature anomalies averaged over the North Atlan tic Ocean from 0-70N and is an important mode of climate variability (Enfield et a l., 2001). Fluctuations in the AMO pattern have a cyclicity of roughly 65 years betwee n troughs (Schlesinger and Ramankutty, 1994; Mann and Park, 1994) with a 0.4C temperature difference between peak and trough (Figure 4, Enfield et al., 2001). T he AMO variability is most likely due to internal variations in the thermohaline circulat ion and associated meridional heat transport (Delworth and Mann, 2000; Collins and Sin ha, 2003; Sutton and Hodson, 2003; Knight et al., 2005).

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54 A negative correlation exists between the phase of the AMO (warm or cold) and the amount of precipitation that falls in the Missi ssippi River basin. During the positive (warm) AMO phase, the central United States receive s below-average precipitation, especially during the summer months (Enfield et al. 2001; Gray et al., 2003). In contrast, during a negative (cool) AMO phase, precipitation i n the Mississippi River Basin increases. The observed periodic oscillation of app roximately 70 years observed in the insoluble residue record most likely results from A MO forcing. Unfortunately, no record of AMO variability extends long enough to compare w ith our record, as the majority of AMO records are instrumental in nature or do not su rpass the extent of the instrumental record. One must also consider this ~70 year cycle as a possible harmonic variant of the larger 200 year cycle. Future work at higher resolu tion is needed to fully understand this periodicity at ~70 years. 3.4 Climate Implications These intervals of increased terrestrial input to t he Gulf of Mexico occur before the accepted onset of both of the abrupt climate ev ents known as the MWP and the LIA. This climatic paradigm of a dry/cold LIA and a wet/ warm MWP is documented at the local and regional scale through the interpretation of marine, lake, and tree ring records (i.e. Keigwin, 1996; Huang et al., 2002; Cook et al ., 2004). While it is unknown if these two climatic events were regional phenomena or wide -scale global events, this record suggests that the Mississippi River basin and subse quent discharge displayed the same response during these contrasting thermal regimes, questioning the accepted paradigm of a warm/wet MWP and cool/dry LIA over the North Amer ica continent. The dry intervals

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55 in these records occur towards the end of both the LIA and MWP, further questioning the accepted paradigm of these thermal regimes. Even though these records show overall synchronicit y, there appear to be some nuances between the records. For example at 1400 BP the insoluble residue and titanium curves tend to decrease, whereas the HMW n-alkane r ecord appears to increase. Some of these asynchronous events may be due to the locatio n within the Mississippi River basin that the material is derived from. For instance, t oday we know that most of the lithic material entering the Gulf of Mexico originated in the Missouri sub-basin, and that most of the water came from the Ohio basin (Turner and R abalais, 2004). Also it appears that all three records begin to increase sharply at 150 BP, most likely due to anthropogenic effects as a result of land-use changes within the basin. Additional work within the Mississippi River basin is needed to constrain wher e the material is coming from within the basin, and subsequently, where the dominant sou rce of moisture was located. 3.5 Summary and Conclusions Assessing the linkages between the ocean and the a tmosphere in the context of changing continental hydrology has critical implica tions for assessing abrupt climate changes. Two distinct intervals exist of increased terrestrial input from the continental USA to the Gulf of Mexico inferred from increased w eight percent of insoluble residues, titanium, and long-chain n-alkane concentrations, l ikely reflecting enhanced precipitation and/or flood-like conditions at 450 and 1200 BP. In contrast, intervals of low Mississippi River terrestrial input reflect drought-like condit ions at 150, 850, and 1400 BP. The linkage between the terrestrial input intervals and increased salinity in the Gulf of Mexico

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56 indicates that continental North America hydrologic variability is directly dependent on the moisture balance (E/P) over the sub-tropical Gu lf of Mexico. The paradigm of a cold/dry LIA and a warm/wet MWP is not reflected in the Mississippi River terrestrial input record; wet intervals are not confined to “wa rm” climate intervals, and conversely dry intervals are not exclusively associated with c old events. More work is needed to examine the influence of periodic oscillations on t errestrial input from the North American continent into the Gulf of Mexico.

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57 Chapter 4 Compound Specific D Analysis of High Molecular Weight N-alkanes as In dicators of North American Hydrologic Variability 4.1 Introduction Better understanding of hydrologic conditions over the past two millennia is needed to accurately predict future hydrologic cond itions. Two abrupt climate events occurred during the Late Holocene, the Little Ice A ge (LIA, 450-150 BP) and the Medieval Warm Period (1100-700 BP), and it is unkno wn how these events impacted the hydrology over North America. Several paleoclimate records exist that suggest tha t the hydrologic conditions over North America have varied over the past 1400 years, (i.e. Laird et al., 1996; Stokes and Swinehart, 1997; Mason, 2004; Daniels and Knox, 200 5; Sridhar, 2006), but most of these records represent a local or regional respons e to varying hydrologic conditions. Therefore, an integrated assessment of hydrologic c onditions over the North American continent is needed to overcome any local or region al effects on the existing paleoarchives. The hydrogen isotope values of individual plant n-alkanes hold great potential for reconstructing past terrestrial hydrologic cond itions (Smith and Freeman, 2006).

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58 4.1.1 Hydrogen Isotopes Hydrogen isotopes of deuterium ( D) in precipitation provide a natural tracer for the hydrologic cycle. The latitudinal distribution of oxygen and hydrogen isotopes in precipitation has been quantified and is represente d by the meteoric water line (Figure 12, Craig, 1961), which relates these two isotopic para meters. Figure 12. Meteoric water line as defined by Craig, 1961. Warmer regions exhibit more enriched D and 18O values. The slope of this line is 8. Precipitation follows the effect of Rayleigh Distil lation, a process associated with a “rain-out” effect observed in condensate from the tropics, where it is evaporated, to higher latitudes. The D values of the residual vapor become progressively more negative with progressing condensation, resulting in more de pleted D values in precipitation with

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59 increasing latitude. North America D values of precipitation vary according to latitud e (Figure 13). Figure 13. Average D of precipitation in North America. Note that valu es get more depleted as latitude increases. (http://www.sahra.arizona.edu/p rograms/isotopes/oxygen.html) Precipitation over the North American continent var ies seasonally, with more enriched values in the southern latitudes and in th e summertime (Figures 14 and 15; Craig and Gordon, 1965; Rozanski et al., 1993; Gat 1996). Precipitation D values over North America in January are extremely depleted ove r the northern regions of the Mississippi River basin (Figure 14). This is due to two factors: an increase in air-mass dominance originating in the Arctic and Pacific reg ions (Hirschboeck, 1991), as well as reduced evaporative enrichment effects.

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60 Figure 14. Map of North America and corresponding D values in precipitation for January (boreal winter). More enriched values are highlight ed in red, and depleted in purple. (www.iaea.org) Precipitation D values over North America in July are enriched re lative to D values in January throughout the Mississippi River basin (Figure 15) due to a shift in the dominant moisture source. The major source of moist ure to the North American continent during the summer months is the Gulf of Mexico (Hir chboeck, 1991).

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61 Figure 15. Map of North America and corresponding D values in precipitation for July (boreal summer). More enriched values are highlighted in re d, and depleted in purple. (www.iaea.org) Evaporation may occur during precipitation, influen cing the isotopic composition of the precipitation, making it more enriched. Upon reaching the ground, the water from precipitation has three paths that it may follow: r unoff into lakes or streams, absorption by soil, or evaporation back into the atmosphere (Y app and Epstein, 1982). It also may evaporate back into the atmosphere once it enters t he soil or a lake or stream (Yapp and Epstein, 1982), leaving the remaining water more en riched. Relative humidity is a measure of how much water v apor is in the air (New et al., 1999). There is a high degree of variability in rel ative humidity throughout North America (Figure 16). Within the Mississippi River b asin, the average annual relative

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62 humidity is greatest in the eastern portion of the basin (Figure 16), and decreases in the western portion of the basin. Relative humidity, in conjunction with temperature and precipitation, has an important influence on the D values of waters and associated plants (Yapp and Epstein, 1982). Figure 16. Average annual relative humidity over No rth America. (http://www.sage.wisc.edu/atlas/maps/avgannrh/atl_a vgannrh_nam.jpg) 4.1.2 Hydrogen Isotopes in Plants Hydrogen isotopes of plants provide important infor mation used to understand plant physiological processes and to reconstruct cl imate histories. Plants serve as recorders of the hydrologic cycle, with their D values reflecting the D of the waters

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63 assimilated during photosynthesis, which almost alw ays is local precipitation (Yapp and Epstein, 1982), with some fractionation. Water is drawn up from the soil by the roots of the plant, which then passes up the plant through the stem with no D fractionation, and transpires in the leaves of th e plant (Yapp and Epstein, 1982). During this transpiration step evaporative enrichment occurs and plant lipid values become more enriched, becaus e all water losses from the leaf of the plant is through evaporation which leaves the heavi er isotopes behind (Craig and Gordon, 1965). Thus, relative humidity plays a critical rol e in determining plant lipid D values (Yapp and Epstein, 1982). Since precipitation provi des water for soils, and soil water is the primary source of water for plants, the D composition of plant waxes reflects the precipitation-evaporative balance of their location (Schefu et al., 2005). In order to reconstruct hydrologic conditions over the North American continent, we analyzed the D values of specific leaf waxes. Compound-specific D analysis of plant lipids eliminates the confounding effects of using bulk analysis, which is a combination of varying organic compounds and source s (Smith and Freeman, 2006). In one single organism, the different compound classes (hydrocarbons, sterols, etc) may have a wide range of hydrogen isotopic values (Sess ions et al., 1999). Most hydrogen in lipid biomarkers is bound to carbon and thus non-ex changeable, making lipids good geochemical proxies for paleoclimatic reconstructio ns (Schimmelmann et al., 1999). Since high-molecular weight n-alkanes are hydrocarb ons unique to higher terrestrial plants (Eglinton and Hamilton, 1967), they are a lo gical choice for D analysis in sediments.

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64 Previous work shows that n-alkane D values from lake sediments have a very strong relationship with the meteoric water line D values (Sachse et al., 2004a). Studies have been done using hydrogen isotopes of sedimenta ry lipids as a proxy for local hydrology (i.e. Sauer et al., 2001; Chikaraishi an d Naraoka, 2003; Huang et al., 2004; Sachse et al., 2004a,b; Schefu et al., 2005), bu t these studies use D values of specific lipids as a proxy for rainfall or relative humidity and do not attempt to suggest an origin location of transported lipids. Smith and Freeman ( 2006) showed seasonal variation in precipitation D values are not present in the leaf wax D values in the Great Plains; they only show a summer signal. This indicates that the soil waters used by plants of the Great Plains are time-averaged and do not preserve season al variations as previously thought (Tang and Feng, 2001). In this study, we have reconstructed D values from high molecular weight nalkanes incorporated into Pigmy Basin sediments spa nning the Late Holocene. This provides an integrated assessment of North American hydrologic conditions to specifically assess how the hydrologic conditions h ave changed over North America during the Late Holocene. 4.2 Results and Discussion This record of D values from high molecular weight n-alkanes found in Pigmy Basin sediments represents an integrated signal of North American hydrology, since it encompasses the entire Mississippi River drainage b asin. D values of high-molecular weight n-alkanes from Pigmy Basin sediments had a 7 0‰ range, from depleted values of -135‰ to enriched values of -66‰ (Figure 17-B). Dep leted peaks of -124‰, -126.5‰,

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65 121‰, and -135‰ occur at 250 BP (during the LIA), 7 50 and 950 BP (during the MWP), and 1300 BP (before the MWP), respectively (Figure 17-B). Conversely, enriched values of -73‰, -85‰, -66‰, and -80‰ occur at 650 BP (bef ore the LIA and after the MWP), 850 BP (during the MWP), and 1200 and 1475 BP (both before the MWP) (Fig 17-B). Figure 17. A. High molecular weight n-alkane terres trial input record. Data has been smoothed using a 3 point running mean and plotted with the r aw data. B. HMW n-alkane C25 and C27 D values (C25, blue curve, and C27, pink curve). The LIA and the MWP are indicated wi th arrows. Purple shaded areas indicate intervals of enriched D values, and yellow areas indicate intervals of depleted D values. Both the C25 and C27 high molecular weight n-alkane D values are very strongly correlated (r = 0.8), with the C27 values being on average 7.22‰ more depleted than C25 values (Figure 17-B). There was no correlation betw een the D values and Gulf of Mexico sea surface temperature (r = 0.18) or salini ty (r = 0.2) records from the same C-25 C-27 Terr. Input LIA MWP Low Temp More Rain High Temp Less Rain

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66 boxcore (Richey et al., 2007). There also appears to be no correlation (r = 0.1) between the D record and the 14C record of solar variability (Stuiver et al., 199 8), even though spectral analysis of the D data revealed a power at 200 years. Therefore, t he E/P balance between the Gulf of Mexico and the North Am erican and/or solar variability are not solely responsible for the D values of plant lipids. Additionally, no systemat ic excursions occur during the LIA or the MWP, and pea k enriched values as well as depleted values occur during both abrupt climate in tervals. The lack of correlation with other records and systematic excursions suggests th at multiple factors are influencing the D values of plant lipids over the North American co ntinent. 4.2.1 Influences on n-alkane D Values Plants reflect the D composition of local source waters in which they grew, and local precipitation has a latitudinal and temperatu re dependence (Dansgaard, 1964). Since depleted values are indicative of “northern source region” latitude, we infer that the more depleted values found in this record represent a no rthern weighted signal. We cannot say specifically where the material is coming from, sin ce the n-alkanes in this study represent an integrated signal over the Mississippi River dra inage basin. Both northern and southern flora is incorporated into the record duri ng intervals of “northern source region” dominance, whereas mostly southern flora would be i ncorporated during intervals of “southern source region” dominance. If depleted val ues represent a “northern source region”, most likely northern storm tracks dominate d over the Mississippi River basin during these intervals, and temperatures were reduc ed. Therefore, relative humidity was most likely low, and evaporative enrichment was min imized.

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67 In contrast, enriched D values observed in this record most likely reflec t a “southern source region” signal, with moisture pred ominantly entering the Mississippi River basin from the Gulf of Mexico. Additional enr ichment may occur due to elevated levels of relative humidity and increased evapo-tra nspiration on the leaf of the plants. These results seem to be independent of influence f rom either climatic event, since enriched and depleted values occur during both the LIA and MWP. Summer rains are much more enriched compared to win ter snow, so terrestrial plants that predominantly grow during the summer mo nths may have D values much more enriched than those plants from the same locat ion that may have a seasonally integrated growth cycle (Sauer et al., 2001). In l ocations where snow is the major source of winter precipitation, snowmelt may be delivered quickly to lakes, streams, and rivers, and subsequently have no effect on terrestrial vege tation ecosystems (Sauer et al., 2001). Presently, North American climate is influenced by many factors and varies on a seasonal basis. The dominant moisture delivery path ways over the continental United States originate from three air-mass source regions : the Pacific Ocean (northwest), the Gulf of Mexico and Atlantic Ocean (south/southeast) and the Arctic (north) region (Figure 3). D values of moisture delivered to the North America n continent via Pacific or Arctic air-masses is going to be much more deple ted than moisture originating from the Gulf of Mexico or Atlantic regions. At present time, we cannot delineate between latitu de/temperature or evaporation as the source of enrichment of D values in these plants. However, given what we kn ow about latitude, associated storm tracks, and season ality, we assume that these factors work together to produce the D signal. The fact that these D high-molecular weight n-

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68 alkane records from the Pigmy Basin do not have any correlation with Gulf of Mexico sea surface temperature or salinity suggest that th ere are other factors besides the hydrologic cycle and temperature that affect the D values of plants. 4.2.2 Metabolic Pathway Influence on n-alkane D Val ues The metabolic pathway used in photosynthesis plays an important role in the D values of plant lipids. There as been some disagree ment as to the degree to which nalkanes originating from plants utilizing the C3 metabolic pathway differ from those using the C4 metabolic pathway. Some of this discrepancy may be explained by the differences in veinal structure of the plants utili zing these pathways. For example, the majority of grasses utilizing the C4 pathway have long parallel veins in their leaves, whereas herbs, shrubs, and trees have branching vei ns (Smith and Freeman, 2006). The fundamental difference in vein structure has bearin g on the isotopic values of oxygen and hydrogen in leaf water (Helliker and Ehleringer, 20 00, 2002a,b), which would influence the lipid isotopic values. It has been found that C4 grasses in the Great Plains region are typically 2 0‰ more enriched than C3 grasses living in the same conditions (Smith and F reeman, 2006). C3 grasses in the Great Plains are typically “cool se ason” grasses whereas C4 grasses in the Great Plains are “warm season” grasses (Smith a nd Freeman, 2006). We are unable to specifically determine which metabolic pathway the plants that synthesized the n-alkanes used in this study used (C3, C4, and CAM) because of the integrated signal. If oth er plant species exhibit a similar seasonal dominance, this would surely lead to hydrogen isotopic variability of n-alkanes occurring in marine sedime nts. It is very possible that the

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69 negative excursions that we are observing in the re cord do not result from a “northern source region” influence but rather an increase in the contribution of C3 plants to the Gulf of Mexico from Mississippi River input. Plants also exhibit a stem to tip enrichment due to evaporation of water through the stomata and back mixing of this enriched stomat al water with vein water, (Helliker and Ehleringer, 2000) so depending on what part of the plant leaf ended up in sediments in the Pigmy Basin would also have an impact on the D composition. Additionally, the slope of the ratio of oxygen and hydrogen isotopes in plant water is approximately 5 (Craig et al., 1963), which differs from the Meter oic Water Line, having a slope of 8 (Craig, 1961; Dansgaard, 1964), due to the effects of evaporation on the D values of plant lipids. 4.3 Future Work Since there are clearly many confounding aspects th at need to be considered when evaluating hydrogen isotopic composition of plant l ipids and subsequent source location, more research is needed before we can say anything concrete about the hydrogen isotopic values observed in this study. A calibration study needs to be done for the modern conditions of n-alkane transport and incorporation into the sediments, and where (latitude) these alkanes came from, the temperature in which they grew, what evaporative effects occur at these latitudes and contribute to isotopic enrichment of the hydrogen isotopic values, what the local source water (preci pitation) hydrogen values are, what local temperatures are, and what the dominant metab olic pathway is that plants are utilizing.

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70 Complementary analysis of 13C of high molecular weight n-alkanes from Pigmy Basin would provide insight into the metabolic path way of plants. This may help constrain what the dominant metabolic pathway of pl ants entering the Gulf of Mexico at any given time was, and take that into account when looking at hydrogen isotopic variations. Once the modern conditions have been ca librated between modern n-alkane values in the Mississippi River basin and the Pigmy Basin, paleo applications can be applied to marine sediments of the Pigmy Basin. 4.4 Summary and Conclusions Compound-specific isotopic analysis of plant lipid s from terrestrial plants found in marine sediments hold great potential as recorde rs of past climates, since the hydrogen isotopic values of plant lipids is derived from the source water of the plant, influenced by local climate and hydrologic conditions. D values of the high-molecular weight nalkanes analyzed in this study ranged from depleted values of -135 ‰ to enriched values of -66‰. It appears that the two abrupt climate int ervals of the LIA and the MWP do not seem to have a significant influence on the D values of these n-alkanes. Future work is needed to constrain the effects of latitude, local precipitation, evaporation, and metabolic pathway on the D values of n-alkanes in modern plants of the Missi ssippi River basin, which can then be applied to n-alkanes found in Pig my Basin sediments.

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71 Chapter 5 Complementary analyses of Pigmy Basin sediments 5.1 Introduction Grain size analysis is a basic sedimentological tec hnique that is used to characterize and interpret marine sediments from Pi gmy Basin. Physical parameters such as bulk dry density, wet water content, and porosit y are used to look at fundamental variations of the marine sediments from Pigmy Basin Bulk dry density provides insight into the origin of the material (terrestrial or mar ine) because terrestrial material is considerably denser than material of marine origin. Wet water content measures of how much water was originally in each sample, and exami nes the ratio of water to sediment. Porosity is a measure of sediment compaction, which will have a bearing on all of the other proxies if the sediment is indeed compacted. Compositional concentrations of the marine sedimen ts are useful for examining differences in sediment origin. Total carbon concen trations includes both the inorganic (calcium carbonate) and organic (biological tissues of both terrestrial and marine organisms) carbon portions. Calcium carbonate perc entages represent calcium carbonate shell production by organisms. There are two forms of calcium carbonate produced by marine fauna; calcite and aragonite, with calcite b eing the dominant form and less soluble in water. Carbonates can be produced as either whol e skeletons (foraminifera) or fragments of skeletons. Skeletal carbonate is preci pitated throughout the marine realm,

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72 and wherever it is not overloaded with terrigenous siliclastic input, carbonate sediments accumulate. Therefore a reduction in CaCO3 in marine sediments from the Pigmy Basin may result from dilution due to increased terrestri al inputs. Bulk organic carbon isotopes of marine sediments f rom the Pigmy Basin provide insight into the dominant source of sedimentary org anic carbon. The carbon isotopic signature of bulk marine sediments is going to inte grate marine and terrestrial organic carbon sources and has the potential to reflect the dominant source of sedimentary organic carbon because marine carbon is more enrich ed (~21‰) relative to organic carbon of terrestrial nature (~27‰, exclusive of C4 plant inputs). Bulk organic nitrogen values can be used to evaluate oceanic productivity and/or degradation throughout the core. Organic lipid biomarker compounds in marine sedime nts are used to characterize the sources of sedimentary organic matter. Low mole cular weight n-alkanes are synthesized by autotrophs as materials of buoyancy regulation, thermal insulation and energy storage (Ohkouchi et al., 1997). Algae show a maximum between C17-C20 (Barker, 1989). These lower molecular weight n-alkanes are u sed as marine biomarkers to reconstruct biological productivity in the overlyin g surface ocean (Ohkouchi, 1997). 5.2 Results and Discussion 5.2.1 Grain Size Analysis Marine sediments can be characterized by their maxi mum grain diameter, and variation in grain size among marine sediments is k nown as sorting. Well-sorted marine sediments show little variation in grain size diame ter, whereas poorly sorted marine

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73 sediments exhibit large deviations from the mean gr ain size. The energy of the depositional environment controls how well sorted t he sediment is. In high energy systems, the sediments tend to be composed of large r grains and the smaller grains are unable to settle out. In low-energy environments, t he small grains are able to settle out and deposit there. The sediments from the Pigmy Basin were determined to have very fine silt as the dominant type of material in the sediments based on phi size (Figure 18-A). This is what would be expected after sediment has been transport ed the 200 kilometers offshore and deposited into the Pigmy Basin. However, there are some intervals where the dominant type of material in the sediments is not very fine silt. For instance, at 172, 493, 986, 999, 1023, 1085, 1122, 1134, 1147, 1159, 1171, 1208, 122 1, 1233, 1245, 1270, 1282, 1332, 1369, 1381, 1393, 1418, and 1430 BP, the phi size d ecreases, indicating that the dominant sediment type was fine silt. Notice that m ost of these values occur during or prior to the MWP, which suggests that the material was deposited in an environment with a higher energy. This may be due to the terrestrial material making its way out to the basin originating in the southern portion of the Mi ssissippi River drainage basin, which is what we would observe with warmer, moist climate do minating over the North American continent and originating in the Gulf of Mexico. Ad ditionally, the dominant sediment type is clay at 530 and 1184 BP, which is before th e onset of the LIA and MWP, respectively, documented by increases in phi size. This suggests that at these intervals the material was deposited under lower energy, and perh aps originated from a location in the northern region of the Mississippi River basin. Thi s may be due to an increased influence of northern air-masses dominating over the North Am erican continent. Determining the

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74 provenance of the material in the sediment core wou ld be critical to either confirm or refute this analysis. Figure 18. Records of core PB-BC1E physical propert ies plotted versus age (years BP). Shaded areas indicate the MWP and LIA. A. Orange curve, av erage phi size B. Black curve, bulk dry density (g/cm3) C. Blue curve, wet water content (%) D. Red curve porosity (%). Arrows indicate an increase in the corresponding physical parameter Terrestrial Input Water % Compaction (A) (B) (C) Size (D)

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75 We do not feel that any slumping or turbidite flow s contributed to the observed grain size variability. If slumping had indeed occu rred, the abundance of benthic foraminifera should increase when the slump occurre d (Brown and Kennett, 2004), which we do not observe (benthic foraminifera data not sh own). 5.2.2 Physical Parameters Dry density (g/cm3) is a proxy for the amount of minerogenic particle s because the density of organic particles is less than that of mineral grains (Mingram et al., 2004). Therefore, dry density is also an indicator of terr estrial inputs into the ocean from continental sources. This may be due to increased e rosion of soils and lithogenic particles due to colder and/or dryer conditions on the contin ent (Mingram et al., 2004), or increased precipitation and/or wet events on the No rth American continent, delivering more material from the continent to the Gulf of Mex ico via Mississippi River discharge. The dry bulk density record shows episodes of signi ficantly increased terrestrial inputs and subsequent enhanced Mississippi River di scharge (wet intervals) centered at ~450 and ~1200 BP (Figure 18-B), which is at the on set of the Little Ice Age (LIA, 450150 BP, Crowley and Lowery, 2000; Mann, 2002a) and before the onset of the Medieval Warm Period (MWP, 1100-700 BP, Mann, 2002b). These inputs peaked at 0.72 and 0.70 g/cm3, respectively. Episodes of decreased terrestrial i nput from the continental USA at ~150, ~850, and ~1400 BP, are interpreted as dry co nditions in the Mississippi River basin and occur after the LIA, during the MWP, and before the MWP, respectively, with lows of ~0.14, ~0.16, and ~0.18 g/cm3. This range of 0.14 to 0.72 g/cm3 is consistent with literature values for dry bulk density of mari ne sediments (Stephens et al., 1992;

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76 Mingram et al., 2004). The average dry bulk densit y throughout the core was determined to be 0.41 g/cm3. The sharp increase in density after 150 BP is mos t likely due to anthropogenic effects of land use change on the Nor th American continent, and terrestrial inputs to the Gulf of Mexico increased. Wet water content is a percentage calculation based on the masses of the sediment. Wet water content and porosity are useful in expressing the degree of consolidation of sedimentary material, in conjuncti on with density data (Stephens et al., 1992). Wet water content results show high values o f water percentage at the core-top (74 BP) followed by a general decrease in the wet water content percent with increasing age (i.e. downcore), and appears to have an inverse rel ationship (r = -0.74) with the bulk dry density before 900 BP and during the LIA (Figure 18 -C). This inverse relationship has been documented in previous studies of bulk paramet ers on marine sediments (Stephens et al., 1992; Mingram et al., 2004). A sharp de crease occurs at 900 BP to ~30 % water, indicating a reduction in the amount of water in th is interval. This corresponds with a decrease in bulk dry density at 900 BP, indicating a reduction in lithogenic particles. After the sharp decrease values remain relatively c onstant throughout the rest of the core, due to sediment becoming more compact, and there is no negative correlation with the bulk dry density. The average wet water content thr oughout the core was determined to be 56.6%. The wet water content values are consiste nt with previously published Late Holocene wet water content values from the Pigmy Ba sin (Bouma et al., 1986). Porosity (void ratio) is a measure of the void spac es in a material per volume of wet saturated sediment (Boyce, 1976). Sediment poro sity consists of the open space between sediment grains. Well-sorted sediment is pr imarily composed of one sediment

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77 size and will typically have higher porosities than poorly sorted sediments. Poorly sorted sediments have a wide range of sediment sizes and t he small sized sediments can infill pore spaces. Marine sediments undergo compaction wh ich typically rearranges the sediment grains to reduce pore volume. Porosity results show peak values of 80% at the cor e-top, 74 years BP, then steadily decrease until reaching a minima of 10% at 900 BP (Figure 18-D). Values than increase again, culminating in the final peak value of 90% at 1350 BP. This porosity record is well correlated with the bulk dry density record (r = 0.73), and the lowest porosity values (most compact) occur during interva ls of decreased terrestrial input, and appear to have more poorly sorted sediment. This su ggests that allochthonous marine sediment particles have less compaction and are wel l sorted than autochthonous marine sediment particles. The average sediment porosity t hroughout the core was determined to be 55.9%. The sediment porosity values in this stud y are consistent with previously published values of Late Holocene sediment porosity values from the Pigmy Basin (Bouma et al., 1986). Since there is no clear trend of increasing compaction with increasing depth, these results suggest that the ef fects of compaction on the sediment and various proxies are minimal, and that the observed variations and trends in all of the proxy data are accurate. 5.2.3 Carbon Concentrations 5.2.3.1 Total Carbon Total carbon percentages represent the combined or ganic and inorganic carbon pools in the sediment. The weight-percent total car bon provides insight into the amount

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78 of carbon being assimilated into the sediment at an y given time. Total carbon weight percentages show maxima at the core-top, 74 BP, of 3.5 wt% (after the LIA) and at the bottom of the core, 1400 BP, also 3.5 wt% (Figure 1 9-B). Total carbon minima occur at 500 and 1200 BP, before the LIA and MWP, respective ly, and correspond with continental inputs into the Gulf of Mexico. These d ecreases in total carbon are most likely due to a reduction in the amount of total in organic carbon fixed by organisms due to increased inputs of terrestrial material from th e North American. The average total carbon value throughout the core was determined to be 2.8 wt%.

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79 Figure 19. Records of core PB-BC1E composition plot ted versus age (years BP). Shaded areas indicate the MWP and LIA. A. Dark blue curve, weigh t percent insoluble residue. B. Pink curve, weight % total carbon C. Light blue curve, weight p ercent total organic carbon D. Yellow curve, (A) B (C) TC TOC CaCO3 Terrestrial Input (B) (D)

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80 weight percent calcium carbonate. Arrows indicate a n increase in the corresponding carbon concentration. 5.2.3.2 Total Organic Carbon Total organic carbon percentages in marine sedimen ts represent the cumulative amount of marine and terrestrial organic matter occ urring in the sediments. The term “organic carbon” is in regards to the carbon presen t in chemical structures that can be traced back to biological productivity. Therefore, the weight-percent of organic carbon provides fundamental insight into the biological pr oductivity of the oceans as well as the amount of biological compounds that are entering th e Gulf of Mexico via Mississippi River fluvial input. Total organic carbon values ar e also used to normalize the n-alkanes to ensure that variations observed are indeed due t o changing terrestrial inputs and not from dilution of marine counterparts. Total organic carbon results show high values of 1 .5 wt % at the core-top (74 BP) most likely due to anthropogenic influences resulti ng from land use change on the North American continent and entering the Gulf of Mexico via Mississippi River discharge (Figure 19-C). High total organic carbon values of 1.2, 1.4, and 1.5 wt% occur at 650 (after the MWP), 1250 (before MWP), and 1450 BP (be fore MWP), respectively. Low values of 0.3 and 0.4 wt% occur at 800 (during MWP) and 1200 BP, respectively (Figure 19-C). The average value throughout the core was de termined to be 0.83 wt%. Since the range of values throughout the core is relatively s mall, and there are no large shifts to an increase or decrease, we assume that the material h as not been degraded and we are observing actual trends in the core.

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81 Increases in total organic carbon may be due to an increase in organic carbon entering the Gulf of Mexico from Mississippi River discharge (i.e. terrestrial land plants) or an increase of organic carbon of marine origin ( algae, zooplankton). Since the analyses were on bulk sediment, we are unable to delineate b etween sources of organic matter using these proxies alone. However, carbon isotopic values are able to do this, and will be discussed further. 5.2.3.3. Calcium Carbonate Calcium carbonate is secreted in the tests of vari ous marine organisms, including foraminifera and coccolithophores. The weight perce nt of calcium carbonate provides information regarding the amount of marine producti vity occurring in the water column. Calcium carbonate results show maximum values at 20 0 (during the LIA), 850 (during the MWP), and 1400 BP, most likely a result of carb onate secretion by marine organisms (Figure 19-D). The average calcium carbonate value throughout the core was determined to be 16.57 wt%, which is higher than previously pu blished calcium carbonate values of 12 wt% from Pigmy Basin sediments (Bouma et al., 1 986). However, the previous study was performed on a core encompassing a much longer time scale (200,000 years), which probably explains the discrepancy in the average va lues. Calcium carbonate minima of 12.5 wt % and 10 wt % occur at 500 and 1250 BP, res pectively, and these values are moderately correlated with the total carbon values (r = 0.67). The minima in the record are most likely due to dilution effects from increa ses of terrestrial input into the Gulf of Mexico from the North American continent. In order to test this, a cross-correlation was applied to the calcium carbonate record and the ins oluble residue record generated on

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82 sediments from the Pigmy Basin (Figure 19-A, Figure 19-D). A very strong negative correlation was observed (r = -0.99), suggesting th at the decreases observed in the calcium carbonate and subsequent total carbon were indeed due to dilution effects from their terrestrial counterparts. 5.2.4 Bulk Organic Carbon Isotopes Many studies have used the 13C values of bulk organic carbon found in marine sediments as indicators of the relative contributio ns of marine and terrestrial organic carbon to sediments (i.e. Jasper and Gagosian, 1993 ). Photosynthetic fixation of carbon (from atmospheric CO2) as organic matter in terrestrial plants results i n an isotopic fractionation because plants preferentially incorpo rate isotopically light carbon (12C) into their tissues. The C3 pathway of photosynthesis involves the maximum frac tionation observed in terrestrial plants, and results in a ca rbon isotopic signature of -23 to -33‰ PDB. The carbon isotopic values produced from marin e phytoplankton range from -10 to -31‰ PDB, but the values for most warm water plankt on range from -17 to -22 ‰ PBD (Anderson and Arthur, 1983). When evaluating the carbon isotopes of bulk marine sediments, isotopically lighter values may result from two factors: the fir st being a terrestrial organic component being relatively depleted in 13C and the other being more resistant and degraded m aterial organic marine or terrestrial material that had los t 13C enriched components (Anderson and Arthur, 1983). Results from bulk organic 13C analyses on Pigmy Basin sediments show four peak depleted values of -25‰ at the core-top (74 BP after the LIA), -25.5‰ at 300 BP

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83 (during the LIA), -25‰ at 950 BP (during the MWP), and -26‰ at 1250 BP (before the MWP, Figure 20-A), suggesting an enhancement of ter restrial material entering the Gulf of Mexico and being assimilated into marine sedimen ts during these intervals. The average 13C value throughout the core was -23.3‰, and the neg ative excursion occurring after 150 BP suggests increased terrestri al input to the Gulf of Mexico due to anthropogenic land use change. The most depleted va lue occurs before the onset of either the MWP or the LIA, and depleted values occur durin g the MWP, LIA and after the LIA, suggesting that the abrupt climate events had the s ame impact on the climate and hydrology of North America, since both intervals ge nerate the same response.

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84 Figure 20. Organic proxies from core PB-BC1E plotte d versus age (years BP). Shaded areas indicate the MWP and LIA. A. Purple curve, bulk org anic carbon isotopes. More depleted values are indicative of material with terrestrial origin. Purple arrow indicates the dominant source (terrestrial or marine) depending on the isotopic v alue. B. Light blue curve, bulk organic nitrogen isotopes. Depleted values are indicative of materia l with marine origin. Light blue arrow indicates the dominant source (terrestrial or marin e) depending on the isotopic value. C. Pink curve, representative low molecular weight n-alkane C17. Pink arrow indicates increased oceanic productivity. The record has been smoothed using a 3pt running mean and plotted with the raw data. D. High molecular weight n-alkane C25 and C27 concentrations. Green arrow indicates Marine Terrestrial Productivity Terrestrial Input (A) (B) (C) (D) Terrestrial Marine

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85 increased terrestrial input. The records have been smoothed using a 3pt running mean and plotted with the raw data. The depleted values indicate increased terrestrial input from the continent into the Gulf of Mexico, and agree well with records of terr estrial input from the Mississippi River to the Gulf of Mexico. This is most likely as a result of intensified atmospheric circulation, in conjunction with a westward, well-d efined Bermuda High, enhancing meridional moisture flux from the Gulf of Mexico. T he warm, moist air masses from the Gulf of Mexico travel northward over the continenta l USA via the Great Plains Low Level Jet where they fall as precipitation due to c onvective processes (thunderstorms and tropical cyclones) as well as convergent processes that occur when the warm, moist tropical air masses meet the cold, dry air coming f rom the north (Arctic region) and northwest (Pacific Ocean) (Hirschboeck, 1991) and c ondense. However, since bulk material is a combination of s ources and compounds, we cannot say for certain whether or not these negativ e excursions results from the addition of more terrestrial material, or a reduction in mar ine contribution resulting from a decrease in productivity. Since there are terrestri al input proxies from the Pigmy Basin, and the terrestrial inputs are enhanced as well dur ing these intervals, we can say with certainty that the amount of terrestrial input was enhanced during these intervals and manifest themselves in the bulk organic carbon isot opic record. Additionally, compoundspecific 13C analysis was performed on sediments from a compan ion Pigmy Basin core, and did not show any isotopic shifts suggestive of C4 plant dominance (data not shown), so the depleted bulk organic carbon 13C values most likely represent a large terrestrial input to the Gulf of Mexico.

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86 5.2.5 Bulk Nitrogen Isotopes Particulate organic matter is the major source of nitrogen to marine sediments (Wedepohl, 1978). After deposition the nitrogen und ergoes a decomposition process, leading to the production of ammonia. Organic nitro gen comprises the bulk of the nitrogen found in “recent” marine sediments. Howeve r, the main nitrogen containing compounds, amino acids and proteins, are less stabl e than hydrocarbons under geologic conditions, and more susceptible to degradation (Eg linton, 1969). Terrestrial material delivered to the ocean via riv ers can affect the composition of 15N of sedimentary organic matter. Nitrogen uptake by terrestrial plants is primarily due to nitrogen fixation of atmospheric nitrogen mediat ed by soil bacteria (Peters et al., 1978). The fraction of organic matter of vascular p lant origin found in soils most likely to survive transport to the ocean has a 15N value corresponding with that of atmospheric nitrogen (approximately 0‰, Peters et al., 1978). Typical marine organic matter has a 15N value of approximately 8‰ (due to the assimilatio n of nitrate or ammonium from the oceans into the tissues of phytoplankton), ther efore the difference between these two potential components can be used to reconstruct the transport of terrestrial organic material from rivers into the oceans (Peters et al ., 1978). It has been shown that the 15N values of organic matter do not appear to change due to selective degradation that occurs during sed imentation (Sweeny et al., 1978). Other factors that must be considered when examinin g 15N values of bulk sediment include anthropogenic fertilizer input to the Gulf of Mexico with 15N values of roughly 7‰. Additionally, there is a consistent 3-3.5 ‰ inc rease in the 15N of organisms with

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87 each trophic level (Ostrom and Fry, 1993), which al so may contribute to the 15N values of bulk marine sediments due to detritus being inco rporated into the sediments Bulk organic 15N analysis data on marine sediments from Pigmy Basi n is difficult to interpret due to the great number of b iogeochemical processes that influence nitrogen. Our results show a general trend of more depleted values with increasing age (i.e. downcore, Figure 20-B). The coretop values ar e the most enriched throughout the entire record (~6.4‰), which is consistent with the values of anthropogenic origin (i.e. fertilizer, animal waste, etc). The most depleted v alue of 2.3‰ occurs at 200 BP during the Little Ice Age. The rapid enrichment following 200 BP is most likely due to anthropogenic factors (i.e. land use change, combus tion of fossil fuels). The average 15N throughout the record was 3.98‰. Since the values do not correspond with the wt% TOC curve, more than likely the enriched 15N values are not due to increased organic matter co ntributions and other factors must be considered. Mineralization is a deg radation process of organic matter by heterotrophic bacteria (decomposers), resulting in the breakdown of large organic molecules into simple organic compounds and ammonia The result is isotopically depleted relative to the consumed biomass (i.e. the organism becomes more enriched). The trend of more depleted values with increasing a ge is indicative of more degradation and/or mineralization occurring on the organic nitr ogen rich molecules by bacteria. Since this decreasing trend remains constant during both the LIA and MWP, there appears to be no abrupt climate event influence on the bulk nitrogen isotopic composition of Pigmy Basin sediments.

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88 Unfortunately, no C/N ratio data are available for sediments from the Pigmy Basin due to a dilutor used during the instrumental analysis. However, the nitrogen remaining fairly constant would suggest that all C/ N ratios would be purely driven by the carbon component, and thus not reveal any new infor mation that has not already been gathered by analysis of all of the proxies discusse d in this thesis. As previously mentioned, organic nitrogen containi ng compounds (amino acids) are more susceptible to degradation than organic ca rbon containing compounds. Therefore, even though the 15N record suggests degradation throughout the core, there is no reason to believe that the organic carbon molecu les have undergone degradation processes, and the records that we have generated a re accurate. 5.2.6 Low Molecular Weight n-alkanes Low molecular weight n-alkanes (C16-C19) are synthesized by marine organisms, and are a useful chemical fossil because they provi de information about organisms that do not necessarily secrete a hard shell or test (Oh kouchi et al., 1997). Previous work from the Pacific Ocean showed that the latitudinal distribution of the LMW n-alkanes positively correlated with nutrient concentrations, suggesting that these compounds can be accurately used as marine biomarkers to reconstr uct biological productivity (Ohkouchi et al., 1997). One representative algal-derived low molecular weig ht n-alkane (C17) shows 3fold increases to 3500 g/g at 200 (during LIA), and 550 BP, and 5-fold inc reases to 5400 g/g at 1250 (before MWP) and 1400 BP (Figure 20-C). Low values of ~200 g/g occur at 100, 350 (during LIA), 850 (during MWP), a nd 1350 BP (Figure 20-C). These

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89 high and low concentrations are synchronous with th e high-molecular weight n-alkane concentration record generated on sediments from Pi gmy Basin (Figure 20-C,D). This suggests that terrestrially-derived nutrient i nput to the Gulf of Mexico supported marine production during the increased in tervals. No systematic increases or decreases occurring during the LIA or the MWP, indi cating that the abrupt climate events did not have an impact on marine productivity. Agai n, the high-molecular weight nalkane concentration increases were most likely due to intensified atmospheric circulation, in conjunction with a westward, well-d efined Bermuda High, enhancing meridional moisture flux from the Gulf of Mexico. T he warm, moist air masses from the Gulf of Mexico travel northward over the continenta l USA via the Great Plains Low Level Jet where they fall as precipitation due to c onvective processes (thunderstorms and tropical cyclones) as well as convergent processes that occur when the warm, moist tropical air masses meet the cold, dry air coming f rom the north (Arctic region) and northwest (Pacific Ocean) (Hirschboeck, 1991) and c ondense, bringing terrestrial material, including plant waxes, to the Gulf of Mex ico via Mississippi River discharge. During the intervals of low concentrations of both algal and terrestrially derived n-alkanes we infer dry conditions on the North Amer ican continent. It has been hypothesized that drought occurring in the Great Pl ains during these times, especially at 850 BP, is due to an intensification of westerly fl ow patterns (zonal flow) which causes an increase in the duration of dry air masses from the Pacific, which block moisture from the Gulf of Mexico entering the Mississippi River b asin region (Bryson and Baerreis, 1968; Bryson et al, 1970; Booth et al., 2006; Shi nker et al., 2006). The reduced Gulf of Mexico meridional moisture flux over the North Amer ica continent results in reduced

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90 duration and/or frequency of warm, moist air masses over the continental USA, causing dry conditions to prevail, reduced terrestrial inpu t to the Gulf of Mexico, and subsequently reduced marine productivity due to red uced nutrient flux to the Gulf of Mexico. 5.3 Summary and Conclusions Multiple proxies in agreement with each other in p aleoclimatic studies give confidence to the results because we can assume tha t all of the components of the climate system are accurately recorded. Grain size analysis is useful for looking at the energy of the environment and sediment transport. Physical pr operties such as dry bulk density, wet water content, and porosity provide insight into th e fundamental changes in the sediment and give information about potential compaction. Ca rbon concentrations (% total carbon, % total organic carbon, and % calcium carbonate) gi ve information regarding how much carbon is being assimilated into the sediment and i nformation about productivity. Bulk isotopes of carbon can be used to delineate between sources of material (marine versus terrestrial), but the problem with using bulk 13C values is that they represent a combination of sources; to completely delineate bet ween sources, it is recommended that compound-specific 13C values be used. 15N values can provide information about productivity and degradation of the material Synchr onous increases between algal derived n-alkanes and terrestrial n-alkanes suggest that nutrients delivered to the Gulf of Mexico via Mississippi River discharge stimulated m arine productivity.

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91 Chapter 6 Summary 6.1 Climate Variability Late Holocene climate variability includes the Lit tle Ice Age (LIA, 450-150 BP) and the Medieval Warm Period (MWP, 1100-700 BP) tha t are characterized by contrasting hydrologic and thermal regimes. The deg ree of interaction between the North American continent and the ocean during these two a brupt climate events is not well known. Marine sedimentary records from basins prox imal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changing climate and hydrologic conditions. The Pigmy Basin in the northern Gulf o f Mexico is ideally situated to record inputs from the Mississippi River and to relate the se inputs to changing hydrologic conditions over North America during the LIA and MW P. 6.2 Terrestrial Inputs into the Gulf of Mexico Assessing the linkages between the ocean and the a tmosphere in the context of changing continental hydrology has critical implica tions for assessing abrupt climate changes. Two distinct intervals exist of increased terrestrial input from the continental USA to the Gulf of Mexico inferred from increased w eight percent of insoluble residues, titanium, and long-chain n-alkane concentrations, l ikely reflecting enhanced precipitation

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92 and/or flood-like conditions. In contrast, interval s of low Mississippi River terrestrial input reflect drought-like conditions. The linkage between the terrestrial input intervals and increased salinity in the Gulf of Mexico indica te that continental North America hydrologic variability is directly dependent on the moisture balance (E/P) over the subtropical Gulf of Mexico. The accepted paradigm of a cold/dry LIA and a warm/wet MWP is not reflected in the Mississippi River terrestri al input record; wet intervals are not confined to “warm” climate intervals, and conversel y dry intervals are not exclusively associated with cold events. More work is needed to examine the influence of periodic oscillations on terrestrial input from the North Am erican continent into the Gulf of Mexico. 6.3 Hydrogen Isotopes of High Molecular n-alkanes f rom the Pigmy Basin Compound-specific isotopic analysis of plant lipid s from terrestrial plants found in marine sediments hold great potential as recorde rs of past climates, since the hydrogen isotopic values of plant lipids is derived from the source water of the plant, influenced by local climate and hydrologic conditions. D values of the high-molecular weight nalkanes analyzed in this study ranged from depleted values of -135 ‰ to enriched values of -66‰. It appears that the two abrupt climate int ervals of the LIA and the MWP do not seem to have a significant influence on the D values of these n-alkanes. Future work is needed to constrain the effects of latitude, local precipitation and temperature, evaporation, and metabolic pathway on the D values of n-alkanes in modern plants of the Mississippi River basin, which can then be appl ied to n-alkanes found in Pigmy Basin sediments.

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93 6.4 Complementary Analyses of Pigmy Basin Sediments Multiple proxies in agreement with each other in p aleoclimatic studies give confidence to the results because we can assume tha t all of the components of the climate system are accurately recorded. Grain size analysis is useful for looking at the energy of the environment and sediment transport. Physical pr operties such as dry bulk density, wet water content, and porosity provide insight into th e fundamental changes in the sediment and give information about potential compaction. Ca rbon concentrations (% total carbon, % total organic carbon, and % calcium carbonate) gi ve information regarding how much carbon is being assimilated into the sediment and i nformation about productivity. Bulk isotopes of carbon can be used to delineate between sources of material (marine versus terrestrial), but the problem with using bulk 13C values is that they represent a combination of sources; to completely delineate bet ween sources, it is recommended that compound-specific 13C values be used. 15N values can provide information about productivity and degradation of the material Synchr onous increases between algal derived n-alkanes and terrestrial n-alkanes suggest that nutrients delivered to the Gulf of Mexico via Mississippi River discharge stimulated m arine productivity. 6.5 Future Work Biogenic silica analysis would reflect the abundanc e of diatoms and other silicious organisms or fragments (sponge spicules, etc), and would remove any uncertainty about the origin of the siliclastic com ponent of the insoluble residue curve. This would further strengthen the notion of increas ed lithic material as an indicator of increased Mississippi River terrestrial input into the Gulf of Mexico. Biogenic silica

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94 analysis would also provide further insight into ma rine autochthonous production over the Late Holocene. Further higher-resolution molecular work in the Pig my Basin is critical to confirm the pattern of terrestrial inputs observed in the p reliminary results. Alkenones are specific long-chain organic molecules that are produced in t he ocean by haptophyte algae, such as certain species of Coccolithophoridae They can be used to reconstruct sea surface temperature (SST) based on their Uk 37 unsaturation index. The most common unicellular marine coccolithophorid Emiliana huxleyi of the family Gephyrocapsaceae contains longchain di, tri, and tetra-unsaturated alkenones whos e Uk 37 unsaturation (the number of double or triple bonds present in a molecule) show temperature dependence. In Quaternary marine sediments, the higher Uk 37 unsaturation values correspond with warmer SST, and low Uk 37 unsaturation values correspond with low SST (Brass ell et. al., 1986). No significant diagenetic effects have been observed in the Uk 37 index (Prahl et. al., 1989), and patterns of temperature changes bas ed on the index appear to behave the same way over several thousands of years (Bard et. al., 1997). Consequently, alkenones are an accurate tool for estimating past changes in sea surface temperature on a global scale (Mix et. al., 2000). Looking at alkenones fro m Pigmy Basin sediments would be an excellent way to generate a complimentary reconstru ction of sea surface temperatures over the Late Holocene. Specific sterols unique to certain organisms allow for marine and terrestrial ecosystem analysis. Changes in ecosystem structure resulting from abrupt climate change can be inferred from specific organism abundance (W erne et. al., 2000). Analysis of certain sterols that are either marine or terrestri al in nature over the Late Holocene from

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95 Pigmy Basin sediments would provide insight into th e dominant ecosystems occurring in the ocean as well as the North American continent, due to the integrated signal. Complementary analysis of 13C of high molecular weight n-alkanes from Pigmy Basin would provide insight into the metabolic path way of plants. This may help constrain what the dominant metabolic pathway of pl ants entering the Gulf of Mexico at any given time was, and take that into account when looking at hydrogen isotopic variations. More research is needed before we can say anything concrete about the hydrogen isotopic values observed in this study. A calibrati on study needs to be done for the modern conditions of n-alkane transport and incorpo ration into the sediments, and where (latitude) these alkanes came from, what evaporativ e effects occur at these latitudes and contribute to isotopic enrichment of the hydrogen i sotopic values, and what the local source water (precipitation) hydrogen values are. O nce the modern conditions have been calibrated between modern n-alkane values in the Mi ssissippi River basin and the Pigmy Basin, paleo applications can be applied to marine sediments of the Pigmy Basin.

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109 Appendix A: Age Model and Inorganic Analyses

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110 Appendix A (Continued) Abbreviations used in Appendix A tables: NPBC Sample: NPBC core sample depth (mm) C14: Radiocarbon age of sample Calibrated Age: Converted radiocarbon age into cal endar age BP Depth: Depth in the core (mm) Age BP: Calendar Age BP Avg m: Average size of sediment in m Avg mm: Average size of sediment in mm Phi: Average phi size of sediment determined from t he logarithmic scale Composition: Sediment composition Dry Density (g/cm3): Bulk dry density of sediment (g/cm3) Wet Water Content (%): Wet water content of the sed iment (%) Porosity (%): Porosity of the sediment (%) %TC: Weight percent of total carbon %TIC: Weight percent of inorganic carbon %CaCO3: Weight percent of calcium carbonate %IR: Weight percent insoluble residues Ti (cps): Titanium (counts per second)

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111 Appendix A (Continued) Table 1. Raw radiocarbon ages converted to calendar years BP. NPBC sample C14 Calibrated Age 15 350 40 100 535 169 230 1000 584 295 1160 704 400 1445 991 500 1680 1239 575 1825 1362

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112 Appendix A (Continued) Figure 21. North Pigmy Basin box-core foraminifera assemblage data.

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113 Appendix A (Continued) Figure 22. Sub-core PB-BC1E foraminifera assemblage data used to compare with the NPBC foraminifera assemblage data to project the ag e model.

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114 Appendix A (Continued) Table 2. Bulk dry density, wet water content, and p orosity analyses. Depth Age BP Dry Density (g/cm3) Wet Water Content (%) Porosity (%) 0 73.998 0.37318869 65.20111364 77.76182841 5 86 0.438315023 62.21880746 80.30767598 10 98.664 0.386460647 64.78461933 75.96098663 15 110.997 0.199567806 69.03996751 47.80371521 20 123.33 0.264743478 66.42978369 54.65234119 25 135.663 0.1316292 69.01703749 34.75624645 30 147.996 0.200998612 59.55419995 32.84982106 40 172.662 0.164784424 64.78868377 37.03813501 45 184.995 0.286649608 64.43704242 56.40828528 50 197.328 0.260599075 61.18362767 45.998433 55 209.661 0.276781982 63.63889729 52.94968229 60 221.994 0.317584616 60.35443382 52.64378587 65 234.327 0.38690469 57.11435272 56.3495729 70 246.66 0.262473924 59.17418156 42.11996251 75 258.993 0.396377611 55.02036729 52.04679449 80 271.326 0.386559323 57.39919624 57.29045106 85 283.659 0.339934789 61.57847747 58.87025802 90 295.992 0.437377598 56.95025886 61.81574444 95 308.325 0.388532849 62.72527413 69.11778785 100 320.658 0.30401663 59.45650085 50.37916566 105 332.991 0.465450995 56.36403738 64.30238625 110 345.324 0.43732826 59.88144278 67.6327101 115 357.657 0.296319882 63.84210919 54.93307516 120 369.99 0.545674796 53.53813881 64.4701359 125 382.323 0.573057459 53.19059105 67.12995454 130 394.656 0.435502749 53.97012638 52.82140315 135 406.989 0.417593008 50.48660157 46.09661588 140 419.322 0.567334236 52.99206496 66.45846258 145 431.655 0.530577328 52.57559322 62.89082232 150 443.988 0.524952781 49.33668075 55.94450684 155 456.321 0.587316179 50.70890748 62.76698361 160 468.654 0.526778292 48.66295485 51.61755275 165 480.987 0.713523118 52.03003982 80.77244117 170 493.32 0.488787931 49.02934672 48.45991236 175 505.653 0.525446162 51.17666317 59.38682825 180 517.986 0.387200719 57.71088679 54.52356867

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115 Appendix A (Continued) Depth Age BP Dry Density (g/cm3) Wet Water Content (%) Porosity (%) 185 530.319 0.500333054 57.30019608 69.63929189 190 542.652 0.205981763 66.40390091 45.21839715 195 554.985 0.362926358 61.46499099 63.43798219 200 567.318 0.47507193 53.15689028 56.20599894 205 579.651 0.410784346 56.92095691 57.67528848 210 591.984 0.499790334 54.92394364 62.86812678 215 604.317 0.29740532 60.07333841 47.12284901 220 616.65 0.408465453 58.30538998 61.3391381 225 628.983 0.466437758 55.72788486 61.78120775 230 641.316 0.38848351 57.26419335 54.6863845 235 653.649 0.56008153 56.06908554 75.18341768 240 665.982 0.308013019 57.60914119 45.07334304 245 678.315 0.368994949 55.08795534 51.31165633 250 690.648 0.349062344 54.66845775 44.3747151 255 702.981 0.501911874 55.64895555 66.46833021 260 715.314 0.481831254 56.87916953 65.66461205 265 727.647 0.351430574 56.73825558 47.92755392 270 739.98 0.331497969 55.49163212 44.97170649 275 752.313 0.495547255 58.17562984 71.51266073 280 764.646 0.284084025 56.42002827 39.58891639 285 776.979 0.53077468 53.35987268 63.35509413 290 789.312 0.339786775 56.24694605 46.00287343 295 801.645 0.397315036 56.47518546 54.04992261 300 813.978 0.329129739 56.59846125 45.62296982 305 826.311 0.361742243 59.59107865 56.03824929 310 838.644 0.330017825 58.4937091 50.76104279 315 850.977 0.387990129 56.32691188 52.95757639 320 863.31 0.369833697 51.08207455 44.49806043 325 875.643 0.440535239 59.48823512 67.86953313 330 887.976 0.264472118 64.72393733 53.68482044 335 900.309 0.282825903 66.61032984 61.8354797 340 912.642 0.225445656 68.31976221 53.98084923 345 924.975 0.202582366 31.49116975 10.75077876 350 937.308 0.378147172 56.7303713 52.75331653 355 949.641 0.365812639 57.6039997 53.5486472 360 961.974 0.345830696 52.52750615 40.65560678 365 974.307 0.349185689 52.28128846 41.49682192 370 986.64 0.474603218 56.85809166 64.53920928

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116 Appendix A (Continued) Depth Age BP Dry Density (g/cm3) Wet Water Content (%) Porosity (%) 375 998.973 0.469768081 55.78874089 62.07575639 380 1011.306 0.336900494 58.05863536 49.96669888 385 1023.639 0.476576743 53.95450192 60.59117203 390 1035.972 0.454127894 55.10648733 57.65160618 395 1048.305 0.308827098 55.36535937 42.86299477 400 1060.638 0.530207292 57.29404731 74.70730472 405 1072.971 0.32619412 62.9951525 59.75686423 410 1085.304 0.345880034 59.02867068 51.64320858 415 1097.637 0.407404684 57.72991646 58.37391642 420 1109.97 0.439030426 55.62902805 58.9393314 425 1122.303 0.362654999 59.49619389 55.37514481 430 1134.636 0.477908873 55.80457373 62.05207409 435 1146.969 0.568987063 53.25083365 66.81320374 440 1159.302 0.455213333 54.2358188 55.56065618 445 1171.635 0.364135143 54.20908978 47.23139289 450 1183.968 0.469176024 51.72397294 53.33451971 455 1196.301 0.504576133 52.06936643 57.67134143 460 1208.634 0.491008147 54.6168507 60.93752571 465 1220.967 0.680022527 53.30920906 79.00761622 470 1233.3 0.37713574 55.13543095 48.21667537 475 1245.633 0.610455762 52.90730479 69.85785981 480 1257.966 0.500925111 50.17648755 54.07459168 485 1270.299 0.469743412 50.99308375 51.61853951 490 1282.632 0.354489538 54.92117698 45.70437774 495 1294.965 0.496435341 52.42552286 58.3374062 500 1307.298 0.447343901 55.67926507 60.52407217 505 1319.631 0.684117592 56.18440376 90.03814219 510 1331.964 0.337911926 58.52291499 49.81621758 515 1344.297 0.439203109 58.38208069 64.25995546 520 1356.63 0.366281351 56.14755226 50.34561573 525 1368.963 0.344079192 56.50830819 50.72206567 530 1381.296 0.392677252 54.82200381 52.64625278 535 1393.629 0.321581005 54.7722215 43.59418587 540 1405.962 0.476700089 54.92466317 62.21044949 545 1418.295 0.357301812 55.41746962 48.66565236 550 1430.628 0.284429392 57.40919635 43.10129794 555 1442.961 0.516274204 53.72399838 65.49735579 560 1455.294 0.498019095 51.66833558 58.55301384

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117 Appendix A (Continued) Depth Age BP Dry Density (g/cm3) Wet Water Content (%) Porosity (%) 565 1467.627 0.502410189 51.85529242 58.66254449 570 1479.96 0.373390976 48.70407442 40.81200866 575 1492.293 0.33783463 54.02804157 41.63644883

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118 Appendix A (Continued) Table 3. Grain size, phi size, and composition. Depth Age BP Avg size (um) Avg Size (mm) Phi Composition 0 74.0 7.4085 0.0074085 7.076602815 very fine silt 5 86.3 7.334 0.007334 7.091184019 very fine silt 10 98.7 5.8935 0.0058935 7.406659616 very fine silt 15 111.0 6.286 0.006286 7.313642013 very fine silt 20 123.3 6.369 0.006369 7.294717413 very fine silt 25 135.7 5.699 0.005699 7.455075492 very fine silt 30 148.0 6.7915 0.0067915 7.202054035 very fine sil t 40 172.7 9.014 0.009014 6.793616835 fine silt 45 185.0 6.802 0.006802 7.199825279 very fine silt 50 197.3 6.565 0.006565 7.250989274 very fine silt 55 209.7 6.2345 0.0062345 7.325510423 very fine sil t 60 222.0 6.0005 0.0060005 7.380701564 very fine sil t 65 234.3 5.841 0.005841 7.4195689 very fine silt 70 246.7 5.313 0.005313 7.556257572 very fine silt 75 259.0 5.3455 0.0053455 7.547459386 very fine sil t 80 271.3 5.1875 0.0051875 7.590744853 very fine sil t 85 283.7 5.1335 0.0051335 7.6058415 very fine silt 90 296.0 5.8495 0.0058495 7.417470973 very fine sil t 95 308.3 5.522 0.005522 7.500593397 very fine silt 100 320.7 5.556 0.005556 7.491737685 very fine silt 105 333.0 4.82 0.00482 7.696751138 very fine silt 110 345.3 4.926 0.004926 7.665367657 very fine silt 115 357.7 4.662 0.004662 7.74483528 very fine silt 120 370.0 5.35 0.00535 7.546245393 very fine silt 125 382.3 5.2715 0.0052715 7.567570747 very fine si lt 130 394.7 6.092 0.006092 7.358868343 very fine silt 135 407.0 4.697 0.004697 7.734044691 very fine silt 140 419.3 5.311 0.005311 7.556800755 very fine silt 145 431.7 4.8855 0.0048855 7.677278064 very fine si lt 150 444.0 5.024 0.005024 7.63694782 very fine silt 155 456.3 4.479 0.004479 7.802607618 very fine silt 160 468.7 4.3505 0.0043505 7.844603066 very fine si lt 165 481.0 4.987 0.004987 7.647612082 very fine silt 170 493.3 10.0155 0.0100155 6.641621744 fine silt 175 505.7 4.771 0.004771 7.711492598 very fine silt 180 518.0 4.6835 0.0046835 7.73819722 very fine sil t

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119 Appendix A (Continued) Depth Age BP Avg size (um) Avg Size (mm) Phi Compos ition 185 530.3 3.855 0.003855 8.019053425 clay 190 542.7 5.743 0.005743 7.443979723 very fine silt 195 555.0 4.1475 0.0041475 7.913542303 very fine si lt 200 567.3 6.2935 0.0062935 7.311921719 very fine si lt 205 579.7 5.16 0.00516 7.598413219 very fine silt 210 592.0 6.4205 0.0064205 7.283098632 very fine si lt 215 604.3 4.772 0.004772 7.711190242 very fine silt 220 616.7 6.002 0.006002 7.380340966 very fine silt 225 629.0 5.0735 0.0050735 7.622802938 very fine si lt 230 641.3 6.3425 0.0063425 7.30073267 very fine sil t 235 653.6 5.121 0.005121 7.609358726 very fine silt 240 666.0 6.635 0.006635 7.235687819 very fine silt 245 678.3 5.649 0.005649 7.467788784 very fine silt 250 690.6 6.399 0.006399 7.287937818 very fine silt 255 703.0 4.3075 0.0043075 7.858933488 very fine si lt 260 715.3 6.6095 0.0066095 7.241243147 very fine si lt 265 727.6 4.3515 0.0043515 7.844271488 very fine si lt 270 740.0 6.4695 0.0064695 7.272130068 very fine si lt 275 752.3 4.6305 0.0046305 7.754616301 very fine si lt 280 764.6 5.9035 0.0059035 7.404213748 very fine si lt 285 777.0 4.2155 0.0042155 7.890080525 very fine si lt 290 789.3 5.5985 0.0055985 7.480743945 very fine si lt 295 801.6 4.636 0.004636 7.752903718 very fine silt 300 814.0 4.5705 0.0045705 7.773432284 very fine si lt 305 826.3 4.351 0.004351 7.844437268 very fine silt 310 838.6 4.3035 0.0043035 7.860273816 very fine si lt 315 851.0 4.039 0.004039 7.951786139 very fine silt 320 863.3 4.3445 0.0043445 7.846594135 very fine si lt 325 875.6 4.5485 0.0045485 7.780393432 very fine si lt 330 888.0 4.6225 0.0046225 7.757110965 very fine si lt 335 900.3 4.793 0.004793 7.704855345 very fine silt 340 912.6 4.388 0.004388 7.832220759 very fine silt 345 925.0 4.325 0.004325 7.853084152 very fine silt 350 937.3 4.467 0.004467 7.80647803 very fine silt 355 949.6 5.713 0.005713 7.451535755 very fine silt 360 962.0 5.1705 0.0051705 7.595480485 very fine si lt 365 974.3 6.484 0.006484 7.268900194 very fine silt 370 986.6 9.167 0.009167 6.769334611 fine silt 375 999.0 7.931 0.007931 6.978281501 fine silt

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120 Appendix A (Continued) Depth Age BP Avg size (um) Avg Size (mm) Phi Compos ition 380 1011.3 4.438 0.004438 7.815874617 very fine sil t 385 1023.6 10.2635 0.0102635 6.606333395 fine silt 390 1036.0 6.6475 0.0066475 7.232972413 very fine s ilt 395 1048.3 7.4495 0.0074495 7.068640688 very fine s ilt 400 1060.6 7.151 0.007151 7.127639281 very fine sil t 405 1073.0 7.2595 0.0072595 7.105914099 very fine s ilt 410 1085.3 9.4985 0.0094985 6.718084583 fine silt 415 1097.6 7.7505 0.0077505 7.0114949 very fine sil t 420 1110.0 7.2015 0.0072015 7.117486848 very fine s ilt 425 1122.3 8.6745 0.0086745 6.849003682 fine silt 430 1134.6 9.0305 0.0090305 6.790978416 fine silt 435 1147.0 8.2265 0.0082265 6.925505524 fine silt 440 1159.3 10.91 0.01091 6.518205088 fine silt 445 1171.6 12.475 0.012475 6.324816374 fine silt 450 1184.0 3.7805 0.0037805 8.04720723 clay 455 1196.3 4.0965 0.0040965 7.93139247 very fine si lt 460 1208.6 12.02 0.01202 6.378419294 fine silt 465 1221.0 11.05 0.01105 6.49980982 fine silt 470 1233.3 12.9 0.0129 6.276485124 fine silt 475 1245.6 9.9385 0.0099385 6.65275616 fine silt 480 1258.0 4.42 0.00442 7.821737915 very fine silt 485 1270.3 10.066 0.010066 6.634365687 fine silt 490 1282.6 9.7525 0.0097525 6.680012191 fine silt 495 1295.0 7.361 0.007361 7.085882513 very fine sil t 500 1307.3 6.636 0.006636 7.235470398 very fine sil t 505 1319.6 6.3295 0.0063295 7.303692746 very fine s ilt 510 1332.0 9.4045 0.0094045 6.732433041 fine silt 515 1344.3 5.536 0.005536 7.496940342 very fine sil t 520 1356.6 5.9345 0.0059345 7.396657801 very fine s ilt 525 1369.0 9.363 0.009363 6.738813427 fine silt 530 1381.3 7.913 0.007913 6.981559527 fine silt 535 1393.6 10.1615 0.0101615 6.620742807 fine silt 540 1406.0 7.062 0.007062 7.145707464 very fine sil t 545 1418.3 9.403 0.009403 6.732663167 fine silt 550 1430.6 7.9265 0.0079265 6.97910031 fine silt 555 1443 7.282 0.007282 7.101449544 very fine silt 560 1455.3 7.7965 0.0077965 7.002957669 very fine s ilt 565 1467.6 5.9285 0.0059285 7.398117157 very fine s ilt 570 1480 6.3185 0.0063185 7.306202179 very fine sil t

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121 Appendix A (Continued) Depth Age BP Avg size (um) Avg Size (mm) Phi Composition 575 1492.3 5.852 0.005852 7.416854515 very fine sil t

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122 Appendix A (Continued) Table 4. Total carbon, total inorganic carbon, calc ium carbonate, and insoluble residue concentrations. Depth Age BP %TC % TIC %CaCO3 %IR 0 74.0 3.064489164 2.001041096 16.66867233 82.26788 5 86.3 3.367542088 1.988609626 16.56511818 82.05595 10 98.7 3.118362445 2.140634921 17.83148889 81.1907 8 15 111.0 3.656536313 2.121041667 17.66827708 80.796 23 20 123.3 2.9833125 2.451740614 20.42299932 79.04543 25 135.7 3.394151515 2.289253012 19.06947759 79.825 62 30 148.0 3.51392283 2.355757576 19.62346061 79.2183 7 40 172.7 3.621886792 2.374166667 19.77680833 78.975 47 45 185.0 3.235547074 2.558478632 21.31212701 78.010 8 50 197.3 3.605990099 2.141596639 17.8395 80.69611 55 209.7 3.301693878 2.511166667 20.91801833 78.291 45 60 222.0 2.994327273 2.166567944 18.04751098 81.124 73 65 234.3 3.076255924 1.888404255 15.73040745 83.081 74 70 246.7 2.478040089 1.899831933 15.8256 83.59619 75 259.0 2.843953488 1.794629213 14.94926135 84.001 41 80 271.3 2.659907121 1.911245421 15.92067436 83.330 66 85 283.7 3.039122807 2.275763689 18.95711153 80.279 53 90 296.0 2.820321101 2.250857788 18.74964537 80.680 89 95 308.3 2.640874126 1.98 16.4934 82.84573 100 320.7 2.712605459 2.105793103 17.54125655 81.85 193 105 333.0 2.651745514 1.844689266 15.36626158 83.82 668 110 345.3 2.612589577 1.929958071 16.07655073 83.24 082 115 357.7 2.95658427 2.179676768 18.15670747 81.066 39 120 370.0 2.4337751 1.933798883 16.10854469 83.3914 8 125 382.3 2.855051546 1.833199426 15.27055122 83.70 76 130 394.7 2.548935632 1.941003861 16.16856216 83.22 351 135 407.0 3.110508475 2.111286307 17.58701494 81.41 376 140 419.3 2.772908309 2.205343511 18.37051145 81.06 192 145 431.7 2.912553191 2.221036468 18.50123378 80.80 725 150 444.0 2.716861199 2.189039548 18.23469944 81.23 748 155 456.3 2.887548638 2.091253644 17.42014286 81.78 356 160 468.7 2.53613806 2.002153846 16.67794154 82.788 07 165 481.0 2.512309927 1.80605 15.0443965 84.24934 170 493.3 2.181197339 1.642944915 13.68573114 85.77 602 175 505.7 2.020471947 1.602773109 13.3511 86.2312 180 518.0 2.098064516 1.540911111 12.83578956 86.60 706

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123 Appendix A (Continued) Depth Age BP %TC % TIC %CaCO3 %IR 185 530.3 2.516861167 1.674111498 13.94534878 85.21 19 190 542.7 2.360441501 1.659476584 13.82343994 85.47 56 195 555.0 2.569749431 1.734947368 14.45211158 84.71 309 200 567.3 2.841039531 2.085429864 17.37163077 81.87 276 205 579.7 2.615509091 2.043433584 17.02180175 82.40 612 210 592.0 2.384233261 1.724697581 14.36673085 84.97 373 215 604.3 2.697101449 1.834158215 15.27853793 83.85 852 220 616.7 2.49988764 1.844538462 15.36500538 83.979 65 225 629.0 3.178194444 1.979548255 16.48963696 82.31 172 230 641.3 2.742029703 1.951127168 16.25288931 82.95 621 235 653.6 3.201742424 2.096363636 17.46270909 81.43 191 240 666.0 2.822269129 2.078917197 17.31738025 81.93 927 245 678.3 2.273681917 1.758373102 14.64724794 84.83 744 250 690.6 2.550666667 1.967654321 16.39056049 83.02 643 255 703.0 2.957119342 2.129343972 17.73743528 81.43 479 260 715.3 2.817785978 2.363310023 19.68637249 79.85 915 265 727.6 3.002942708 2.275757576 18.95706061 80.31 575 270 740.0 2.734868035 2.088076923 17.39368077 81.95 953 275 752.3 2.721958763 2.224793814 18.53253247 80.97 03 280 764.6 2.60971867 2.250859599 18.74966046 80.891 48 285 777.0 2.954186603 2.083902439 17.35890732 81.77 081 290 789.3 2.556885246 2.303184855 19.18552984 80.56 077 295 801.6 3.110833333 2.095472155 17.45528305 81.52 936 300 814.0 3.124541667 2.349217791 19.5689842 79.655 69 305 826.3 2.957267442 2.265012107 18.86755085 80.44 019 310 838.6 2.8221843 2.31314587 19.2685051 80.22246 315 851.0 3.242441113 2.526924829 21.04928383 78.23 52 320 863.3 3.13026616 2.501598513 20.83831561 78.533 02 325 875.6 3.192099323 2.407326478 20.05302956 79.16 22 330 888.0 3.00072 2.124514388 17.69720486 81.42659 335 900.3 2.595558511 2.198738318 18.31549019 81.28 769 340 912.6 3.036342282 2.155128866 17.95222345 81.16 656 345 925.0 2.737591036 2.318823529 19.3158 80.26543 350 937.3 2.803065903 2.105756208 17.54094921 81.76 174 355 949.6 2.734609164 1.768405063 14.73081418 84.30 298 360 962.0 2.395111821 1.760595855 14.66576347 84.69 972 365 974.3 2.699381443 1.83286119 15.26773371 83.865 75 370 986.6 2.705886076 2.006207675 16.71170993 82.58 861 375 999.0 2.48381733 1.618642241 13.48328987 85.651 54

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124 Appendix A (Continued) Depth Age BP %TC % TIC %CaCO3 %IR 380 1011.3 2.481746032 1.882454212 15.68084359 83.7 1986 385 1023.6 2.649222222 1.80480315 15.03401024 84.12 157 390 1036.0 2.464120055 1.726320166 14.38024699 84.8 8195 395 1048.3 2.786527778 1.791647059 14.92442 84.0807 400 1060.6 2.517477204 1.813598015 15.10727146 84.1 8885 405 1073.0 3.032310127 2.054734177 17.1159357 81.90 649 410 1085.3 2.792047244 2.0517737 17.09127492 82.168 45 415 1097.6 2.969845361 1.969238281 16.40375488 82.5 9564 420 1110.0 2.85237785 2.247133106 18.71861877 80.67 614 425 1122.3 3.253144876 2.104956672 17.53428908 81.3 1752 430 1134.6 2.575527638 2.015228758 16.78685556 82.6 5285 435 1147.0 2.839302326 1.790696721 14.91650369 84.0 3489 440 1159.3 2.116283186 1.739341637 14.48871584 85.1 3434 445 1171.6 2.477511848 1.583602694 13.19141044 85.9 1468 450 1184.0 2.364841629 1.396389961 11.63192838 87.3 9962 455 1196.3 2.60228866 1.359857143 11.32761 87.42996 460 1208.6 2.595138593 1.504043478 12.52868217 86.3 8022 465 1221.0 2.01748503 1.586025878 13.21159556 86.35 695 470 1233.3 2.435034483 1.647003891 13.71954241 85.4 9243 475 1245.6 2.683354701 1.307423888 10.89084098 87.7 3323 480 1258.0 2.312783964 1.154274406 9.615105805 89.2 2638 485 1270.3 2.61124774 1.316990741 10.97053287 87.73 521 490 1282.6 2.359095128 1.276098765 10.62990272 88.2 871 495 1295.0 2.825125523 1.630077519 13.57854574 85.2 2641 500 1307.3 2.501111111 1.675075758 13.95338106 85.2 2058 505 1319.6 2.749490446 1.676536145 13.96554608 84.9 615 510 1332.0 3.00646 2.119006623 17.65132517 81.46122 515 1344.3 2.998655462 1.864133739 15.52823404 83.3 3724 520 1356.6 3.070306407 2.139543269 17.82239543 81.2 4684 525 1369.0 3.08608547 2.157127072 17.96886851 81.10 217 530 1381.3 2.899757869 2.070446927 17.24682291 81.9 2387 535 1393.6 3.304463768 2.181615202 18.17285463 80.7 043 540 1406.0 2.729329759 2.096519481 17.46400727 81.9 0318 545 1418.3 3.196720978 2.334705882 19.4481 79.68988 550 1430.6 2.840978593 2.065184534 17.20298717 82.0 2122 555 1443.0 3.24526149 2.27859116 18.98066436 80.052 67 560 1455.3 3.790460829 2.319654605 19.32272286 79.2 0647 565 1467.6 3.443797468 2.131806167 17.75794537 80.9 3006 570 1480.0 2.788407311 1.923411306 16.02201618 83.1 1299

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125 Appendix A (Continued) Depth Age BP %TC % TIC %CaCO3 %IR 575 1492.3 3.531434263 2.228812785 18.5660105 80.13 137

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126 Appendix A (Continued) Table 5. Elemental titanium XRF analyses. Depth Age BP Ti (cps) 34.941 147.870803 42.37 35.501 149.252099 41.57 36.061 150.633395 41.97 36.621 152.014691 42 37.181 153.395987 43.8 37.741 154.777283 44.47 38.301 156.158579 40.17 38.861 157.539875 44.17 39.42 158.918704 42.93 39.98 160.3 47.5 40.54 161.681296 40.37 41.1 163.062592 41.73 41.66 164.443888 45.93 42.22 165.825184 48.3 42.78 167.20648 43.9 43.34 168.587776 44.1 43.9 169.969072 43.27 44.46 171.350368 42.3 45.019 172.729197 41.4 45.579 174.110493 44.2 46.139 175.491789 47.73 46.699 176.873085 42.53 47.259 178.254381 41.9 47.819 179.635677 40.93 48.379 181.016973 37.23 48.939 182.398269 33.8 49.499 183.779565 36.1 50.059 185.160861 39 50.618 186.539691 35.1 51.178 187.920987 40.7 51.738 189.302283 47.37 52.298 190.683579 42.57 52.858 192.064875 45.67 53.418 193.446171 43.27 53.978 194.827467 38.03 54.538 196.208763 43.13

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127 Appendix A (Continued) Depth Age BP Ti (cps) 55.098 197.590059 45.4 55.658 198.971355 44.6 56.218 200.352651 44.03 56.777 201.73148 45.1 57.337 203.112776 46.87 57.897 204.494072 43.03 58.457 205.875368 47.17 59.017 207.256664 49.53 59.577 208.63796 43.53 60.137 210.019256 49.2 60.697 211.400552 36.73 61.257 212.781848 47.73 61.817 214.163144 48.3 62.376 215.541974 41.3 62.936 216.92327 44.97 63.496 218.304566 47.13 64.056 219.685862 49.4 64.616 221.067158 49.13 65.176 222.448454 49.87 65.736 223.82975 39.2 66.296 225.211046 44.73 66.856 226.592342 47.93 67.416 227.973638 48.37 67.975 229.352467 44.37 68.535 230.733763 46.37 69.095 232.115059 48.37 69.655 233.496355 47.1 70.215 234.877651 50.07 70.775 236.258947 55.77 71.335 237.640243 54.53 71.895 239.021539 54.5 72.455 240.402835 50.67 73.015 241.784131 46.1 73.574 243.16296 54.93 74.134 244.544256 48.53 74.694 245.925552 50.67 75.254 247.306848 54.7 75.814 248.688144 49.33 76.374 250.06944 52.97

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128 Appendix A (Continued) Depth Age BP Ti (cps) 76.934 251.450736 48.5 77.494 252.832032 47.77 78.054 254.213328 48.53 78.614 255.594624 45.43 79.173 256.973454 47.83 79.733 258.35475 45.83 80.293 259.736046 47.7 80.853 261.117342 44.47 81.413 262.498638 53.97 81.973 263.879934 46.57 82.533 265.26123 47.9 83.093 266.642526 49.6 83.653 268.023822 45.3 84.213 269.405118 47.93 84.772 270.783947 45.17 85.22 271.888984 53.2 85.78 273.27028 40.03 86.34 274.651576 46.8 86.9 276.032872 46.87 87.46 277.414168 48.5 88.02 278.795464 48.07 88.58 280.17676 44.4 89.14 281.558056 47 89.7 282.939352 37.8 90.259 284.318181 44.13 90.819 285.699477 48.17 91.379 287.080773 49.7 91.939 288.462069 42.47 92.499 289.843365 46.37 93.059 291.224661 46.17 93.619 292.605957 46.5 94.179 293.987253 31.9 94.739 295.368549 33.93 95.299 296.749845 39.87 95.858 298.128675 39.47 96.418 299.509971 27.97 96.978 300.891267 44.23 97.538 302.272563 48.53 98.098 303.653859 44.43

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129 Appendix A (Continued) Depth Age BP Ti (cps) 98.658 305.035155 49.47 99.218 306.416451 48 99.778 307.797747 51.8 100.34 309.183976 47.57 100.9 310.565272 43.5 101.46 311.946568 45.33 102.02 313.327864 50 102.58 314.70916 48.57 103.14 316.090456 51.87 103.7 317.471752 50.1 104.26 318.853048 49.5 104.82 320.234344 45.47 105.38 321.61564 47.97 105.94 322.996936 42.03 106.5 324.378232 50.43 107.06 325.759528 35.27 107.62 327.140824 48.9 108.18 328.52212 55.6 108.74 329.903416 45.97 109.3 331.284712 48.3 109.86 332.666008 46.87 110.42 334.047304 47.57 110.98 335.4286 42.03 111.54 336.809896 44.47 112.1 338.191192 43.53 112.66 339.572488 44.73 113.22 340.953784 47.2 113.78 342.33508 42.23 114.34 343.716376 45.67 114.9 345.097672 43.57 115.45 346.454302 45.03 116.01 347.835598 44.17 116.57 349.216894 47.7 117.13 350.59819 45.23 117.69 351.979486 46.37 118.25 353.360782 45.27 118.81 354.742078 53.23 119.37 356.123374 50.83 119.93 357.50467 47.9

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130 Appendix A (Continued) Depth Age BP Ti (cps) 120.49 358.885966 43.17 121.05 360.267262 45.87 121.61 361.648558 46.57 122.17 363.029854 44.4 122.73 364.41115 42.13 123.29 365.792446 50.9 123.85 367.173742 51.97 124.41 368.555038 51.83 124.97 369.936334 46.27 125.53 371.31763 47.53 126.09 372.698926 45.13 126.65 374.080222 44.9 127.21 375.461518 45.87 127.77 376.842814 41.67 128.33 378.22411 44.9 128.89 379.605406 39.9 129.45 380.986702 51.4 130.01 382.367998 48.17 130.57 383.749294 45.63 131.13 385.13059 44.33 131.69 386.511886 46.47 132.25 387.893182 42.97 132.81 389.274478 44.53 133.37 390.655774 47.27 133.93 392.03707 48.37 134.49 393.418366 51.37 135.05 394.799662 44.33 135.61 396.180958 47.27 136.17 397.562254 46.03 136.73 398.94355 41.97 137.29 400.324846 40.13 137.85 401.706142 48.37 138.41 403.087438 35.73 138.97 404.468734 42.07 139.53 405.85003 36.33 140.09 407.231326 46.63 140.65 408.612622 45.63 141.21 409.993918 44.63 141.77 411.375214 37.5

PAGE 141

131 Appendix A (Continued) Depth Age BP Ti (cps) 142.33 412.75651 40.13 142.89 414.137806 41.17 143.45 415.519102 41.07 144.01 416.900398 45.63 144.57 418.281694 44.8 145.13 419.66299 48.97 145.69 421.044286 43.5 146.25 422.425582 49.63 146.81 423.806878 46.83 147.37 425.188174 48.73 147.93 426.56947 46.43 148.49 427.950766 49.97 149.05 429.332062 45.13 149.61 430.713358 41.33 150.17 432.094654 43.37 150.73 433.47595 46.47 151.29 434.857246 42.2 151.85 436.238542 47 152.41 437.619838 48.17 152.97 439.001134 42.07 153.53 440.38243 43.27 154.09 441.763726 44.1 154.65 443.145022 48.23 155.21 444.526318 50.13 155.77 445.907614 47.8 156.33 447.28891 47.8 156.89 448.670206 48 157.45 450.051502 44.63 158.01 451.432798 48.97 158.57 452.814094 51.47 159.13 454.19539 48.8 159.69 455.576686 45.37 160.25 456.957982 45.73 160.81 458.339278 47.67 161.37 459.720574 42.5 161.93 461.10187 49.33 162.49 462.483166 50 163.05 463.864462 46.2 163.61 465.245758 49.23

PAGE 142

132 Appendix A (Continued) Depth Age BP Ti (cps) 164.17 466.627054 48.53 164.73 468.00835 47.4 165.29 469.389646 49.57 165.85 470.770942 46.93 166.41 472.152238 43.13 166.97 473.533534 48.4 167.53 474.91483 52.57 168.09 476.296126 53.1 168.65 477.677422 51.17 169.21 479.058718 47.2 169.77 480.440014 54.2 170.33 481.82131 49.13 170.89 483.202606 54.13 171.45 484.583902 46.67 172 485.940532 48.83 172.56 487.321828 50.53 173.12 488.703124 48.33 173.68 490.08442 50.27 174.24 491.465716 55 174.8 492.847012 53.07 175.36 494.228308 50.7 175.92 495.609604 53.73 176.48 496.9909 51.17 177.04 498.372196 49.8 177.6 499.753492 55.13 178.16 501.134788 58.8 178.72 502.516084 59.13 179.28 503.89738 55.47 179.84 505.278676 49.93 180.4 506.659972 51.17 180.96 508.041268 46.17 181.52 509.422564 55.17 182.08 510.80386 52.3 182.64 512.185156 57.9 183.2 513.566452 47.73 183.76 514.947748 52.87 184.32 516.329044 50.3 184.88 517.71034 53.57 185.44 519.091636 49.4

PAGE 143

133 Appendix A (Continued) Depth Age BP Ti (cps) 186 520.472932 54.4 186.56 521.854228 49.5 187.12 523.235524 53.2 187.68 524.61682 55.53 188.24 525.998116 47.97 188.8 527.379412 51.83 189.36 528.760708 52.6 189.92 530.142004 51.03 190.48 531.5233 52.77 191.04 532.904596 55.6 191.6 534.285892 47.37 192.16 535.667188 46.43 192.72 537.048484 46.47 193.28 538.42978 56.1 193.84 539.811076 48.23 194.4 541.192372 48.2 194.96 542.573668 52.53 195.52 543.954964 46.87 196.08 545.33626 53.1 196.64 546.717556 47.83 197.2 548.098852 49.3 197.76 549.480148 60.7 198.32 550.861444 52.33 198.88 552.24274 47.33 199.44 553.624036 44.83 200 555.005332 41.5 200.5 556.238632 46.4 201.01 557.496598 48.33 201.51 558.729898 41.63 202.01 559.963198 44.37 202.52 561.221164 49.67 203.02 562.454464 41.1 203.53 563.71243 43.67 204.03 564.94573 49.57 204.53 566.17903 47.37 205.04 567.436996 42.63 205.54 568.670296 40.7 206.04 569.903596 46.97 206.55 571.161562 48.27

PAGE 144

134 Appendix A (Continued) Depth Age BP Ti (cps) 207.05 572.394862 48.6 207.56 573.652828 45.73 208.06 574.886128 45.03 208.46 575.872768 47.2 208.97 577.130734 47.6 209.47 578.364034 48.2 209.97 579.597334 48.43 210.48 580.8553 45.1 210.98 582.0886 44.77 211.48 583.3219 38.77 211.99 584.579866 46.23 212.49 585.813166 44.93 213 587.071132 44.67 213.5 588.304432 41.5 214 589.537732 42.87 214.51 590.795698 45.03 215.01 592.028998 47.63 215.51 593.262298 47.23 216.02 594.520264 43.1 216.52 595.753564 50.33 217.03 597.01153 50.03 217.53 598.24483 48.77 218.03 599.47813 50.7 218.54 600.736096 45.23 219.04 601.969396 42.77 219.54 603.202696 44.7 220.05 604.460662 42.1 220.55 605.693962 45.13 221.06 606.951928 41.07 221.56 608.185228 42 222.06 609.418528 43.67 222.57 610.676494 46.03 223.07 611.909794 41.3 223.57 613.143094 39.57 224.08 614.40106 41.17 224.58 615.63436 46.53 225.08 616.86766 46.7 225.59 618.125626 50.27 226.09 619.358926 41.93

PAGE 145

135 Appendix A (Continued) Depth Age BP Ti (cps) 226.6 620.616892 42.87 227.1 621.850192 45.97 227.6 623.083492 47.7 228.11 624.341458 45.93 228.61 625.574758 49.6 229.11 626.808058 51.47 229.62 628.066024 50.37 230.12 629.299324 44.27 230.63 630.55729 49.97 231.13 631.79059 47.6 231.63 633.02389 50.97 232.14 634.281856 51.87 232.64 635.515156 52.97 233.14 636.748456 46.23 233.65 638.006422 45.73 234.15 639.239722 51.77 234.66 640.497688 49.4 235.16 641.730988 44.07 235.66 642.964288 51 236.17 644.222254 61.6 236.67 645.455554 45.8 237.17 646.688854 51.47 237.68 647.94682 51.2 238.18 649.18012 51.6 238.69 650.438086 50.3 239.19 651.671386 51.8 239.69 652.904686 49.3 240.2 654.162652 51.3 240.7 655.395952 52.87 241.2 656.629252 54.83 241.71 657.887218 47.7 242.21 659.120518 50 242.71 660.353818 49.57 243.22 661.611784 48.13 243.72 662.845084 47.23 244.23 664.10305 55.27 244.73 665.33635 45.27 245.23 666.56965 50.3 245.74 667.827616 45.97

PAGE 146

136 Appendix A (Continued) Depth Age BP Ti (cps) 246.24 669.060916 54.1 246.74 670.294216 53.2 247.25 671.552182 45.83 247.75 672.785482 51.13 248.26 674.043448 42.1 248.76 675.276748 43.47 249.26 676.510048 44.1 249.77 677.768014 45.7 250.27 679.001314 39.4 250.77 680.234614 48.67 251.28 681.49258 46.7 251.78 682.72588 50.63 252.29 683.983846 46.1 252.79 685.217146 45.4 253.29 686.450446 45.5 253.8 687.708412 49.5 254.3 688.941712 51.57 254.8 690.175012 55.27 255.31 691.432978 47.27 255.81 692.666278 45.97 256.31 693.899578 49.5 256.82 695.157544 50.67 257.32 696.390844 50.37 257.83 697.64881 40.77 258.33 698.88211 48.33 258.83 700.11541 50.97 259.34 701.373376 45.73 259.84 702.606676 47.13 260.33 703.81531 47.27 260.83 705.04861 48.27 261.32 706.257244 45.9 261.81 707.465878 46.4 262.31 708.699178 50.5 262.8 709.907812 48.37 263.3 711.141112 45.1 263.79 712.349746 46.3 264.28 713.55838 49.07 264.78 714.79168 49.5 265.27 716.000314 48.57

PAGE 147

137 Appendix A (Continued) Depth Age BP Ti (cps) 265.77 717.233614 43.63 266.26 718.442248 47.73 266.75 719.650882 44.37 267.25 720.884182 47.83 267.74 722.092816 50.13 268.23 723.30145 49.83 268.73 724.53475 50.53 269.22 725.743384 44.33 269.72 726.976684 43.67 270.21 728.185318 46.23 270.7 729.393952 49.43 271.2 730.627252 50.53 271.69 731.835886 45.23 272.19 733.069186 45.8 272.68 734.27782 48.93 273.17 735.486454 48.7 273.67 736.719754 48.5 274.16 737.928388 46.27 274.66 739.161688 49.77 275.15 740.370322 51.3 275.64 741.578956 46.27 276.14 742.812256 48.5 276.63 744.02089 46.33 277.12 745.229524 46.9 277.62 746.462824 46.47 278.11 747.671458 51.13 278.61 748.904758 49.7 279.1 750.113392 45.5 279.59 751.322026 42.53 280.09 752.555326 49 280.58 753.76396 48.47 281.08 754.99726 47.03 281.57 756.205894 47.07 282.06 757.414528 48.1 282.56 758.647828 48.47 283.05 759.856462 46.43 283.55 761.089762 49.33 284.04 762.298396 49.9 284.53 763.50703 48.83

PAGE 148

138 Appendix A (Continued) Depth Age BP Ti (cps) 285.03 764.74033 49.07 285.52 765.948964 49.3 286.01 767.157598 49.67 286.51 768.390898 46.8 287 769.599532 50.13 287.5 770.832832 46.87 287.99 772.041466 48.37 288.48 773.2501 50.07 288.98 774.4834 49.13 289.47 775.692034 45.87 289.97 776.925334 47.3 290.46 778.133968 50.7 290.95 779.342602 50.1 291.45 780.575902 48.13 291.94 781.784536 46.03 292.44 783.017836 42.33 292.93 784.22647 48.47 293.42 785.435104 49.73 293.92 786.668404 48.63 294.41 787.877038 47.6 294.9 789.085672 49.03 295.4 790.318972 47.4 295.89 791.527606 42.53 296.39 792.760906 40.63 296.88 793.96954 45.77 297.37 795.178174 48.53 297.87 796.411474 50.23 298.36 797.620108 49.87 298.86 798.853408 42.67 299.35 800.062042 52.53 299.84 801.270676 47.77 300.34 802.503976 50.37 300.83 803.71261 43.9 301.33 804.94591 47.53 301.82 806.154544 40.13 302.31 807.363178 42.77 302.81 808.596478 48.53 303.3 809.805112 48.83 303.79 811.013746 43.97

PAGE 149

139 Appendix A (Continued) Depth Age BP Ti (cps) 304.29 812.247046 43.77 304.78 813.45568 43.53 305.28 814.68898 40.83 305.77 815.897614 41.83 306.26 817.106248 41.1 306.76 818.339548 46.13 307.25 819.548182 46.23 307.75 820.781482 41.53 308.24 821.990116 46.27 308.73 823.19875 44.07 309.23 824.43205 43.9 309.72 825.640684 48.13 310.22 826.873984 48.37 310.71 828.082618 47.03 311.2 829.291252 44.03 311.7 830.524552 40.43 312.19 831.733186 48.57 312.68 832.94182 44.4 313.18 834.17512 45.6 313.67 835.383754 45.43 314.17 836.617054 46.1 314.66 837.825688 42.17 315.15 839.034322 46.17 315.65 840.267622 39.27 316.14 841.476256 44.3 316.64 842.709556 50.4 317.13 843.91819 42.73 317.62 845.126824 47.07 318.12 846.360124 42.17 318.61 847.568758 44.57 319.01 848.555398 43.37 319.5 849.764032 43.67 319.99 850.972666 46.53 320.49 852.205966 44.73 320.98 853.4146 44.3 321.48 854.6479 44.2 321.97 855.856534 39.13 322.46 857.065168 46.03 322.96 858.298468 41.93

PAGE 150

140 Appendix A (Continued) Depth Age BP Ti (cps) 323.45 859.507102 40.3 323.95 860.740402 46.7 324.44 861.949036 49.7 324.93 863.15767 45.17 325.43 864.39097 41.37 325.92 865.599604 49.13 326.64 867.375556 50.47 327.41 869.274838 49.93 328.17 871.149454 42.97 328.94 873.048736 41.4 329.71 874.948018 47.67 330.47 876.822634 49.87 331.24 878.721916 48.5 332.01 880.621198 48.97 332.77 882.495814 46.3 333.54 884.395096 50.7 334.31 886.294378 50.5 335.08 888.19366 46.07 335.84 890.068276 50.97 336.61 891.967558 39.17 337.38 893.86684 48.27 338.14 895.741456 44.53 338.91 897.640738 47.17 339.68 899.54002 50.8 340.44 901.414636 44.63 341.21 903.313918 43.5 341.98 905.2132 42.3 342.75 907.112482 41.07 343.51 908.987098 45.77 344.28 910.88638 46.23 345.05 912.785662 44.4 345.81 914.660278 48.63 346.58 916.55956 52.83 347.35 918.458842 43.27 348.11 920.333458 46.9 348.88 922.23274 38.7 349.65 924.132022 45.47 350.42 926.031304 47.47 351.18 927.90592 56.87

PAGE 151

141 Appendix A (Continued) Depth Age BP Ti (cps) 351.95 929.805202 57.77 352.72 931.704484 54.9 353.23 932.96245 55.17 353.6 933.875092 56.47 353.98 934.8124 57.53 354.35 935.725042 52.67 354.72 936.637684 51.4 355.1 937.574992 54.6 355.47 938.487634 56.73 355.85 939.424942 58.47 356.22 940.337584 61.27 356.59 941.250226 53.13 356.97 942.187534 53.77 357.34 943.100176 45.63 357.71 944.012818 45.73 358.09 944.950126 48.17 358.46 945.862768 57.8 358.84 946.800076 53.63 359.21 947.712718 52.1 359.58 948.62536 48.97 359.96 949.562668 54.53 360.33 950.47531 55.67 360.7 951.387952 56.9 361.08 952.32526 52.73 361.45 953.237902 43.5 361.83 954.17521 48.9 362.2 955.087852 47.77 362.57 956.000494 51.2 362.95 956.937802 50.47 363.32 957.850444 43.63 363.69 958.763086 52.2 364.07 959.700394 51.83 364.44 960.613036 53.9 364.82 961.550344 52.43 365.11 962.265658 51.6 365.49 963.202966 50.73 365.86 964.115608 49.87 366.24 965.052916 54.43 366.61 965.965558 53.77

PAGE 152

142 Appendix A (Continued) Depth Age BP Ti (cps) 366.98 966.8782 50.17 367.36 967.815508 51.73 367.73 968.72815 47.53 368.1 969.640792 51 368.48 970.5781 54.7 368.85 971.490742 49.67 369.23 972.42805 43.7 369.67 973.513354 47.77 370.13 974.64799 53.37 370.58 975.75796 48.63 371.04 976.892596 41.6 371.5 978.027232 53.77 371.95 979.137202 56.03 372.41 980.271838 53.43 372.87 981.406474 54.5 373.32 982.516444 52.6 373.78 983.65108 53.73 374.23 984.76105 48.07 374.69 985.895686 48.33 375.15 987.030322 51 375.6 988.140292 46.9 376.06 989.274928 49.23 376.52 990.409564 54.13 376.97 991.519534 50.4 377.43 992.65417 46.97 377.89 993.788806 51 378.34 994.898776 49.1 378.8 996.033412 48.77 379.25 997.143382 49.2 379.71 998.278018 47.93 380.17 999.412654 52.93 380.62 1000.52262 46.03 381.08 1001.65726 47.07 381.54 1002.7919 47.43 381.99 1003.90187 50.07 382.45 1005.0365 49.93 382.91 1006.17114 51.03 383.36 1007.28111 51.93 383.82 1008.41574 51.33

PAGE 153

143 Appendix A (Continued) Depth Age BP Ti (cps) 384.27 1009.52571 53 384.73 1010.66035 49.83 385.19 1011.79499 48.13 385.64 1012.90496 51 386.1 1014.03959 51.33 386.56 1015.17423 47.93 387.01 1016.2842 46.7 387.47 1017.41883 51.77 387.93 1018.55347 55.07 388.38 1019.66344 48.57 388.84 1020.79808 48 389.29 1021.90805 49.07 389.75 1023.04268 48.07 390.21 1024.17732 43.17 390.66 1025.28729 48.83 391.12 1026.42192 51.83 391.58 1027.55656 56 392.03 1028.66653 53 392.49 1029.80117 47.3 392.95 1030.9358 48.47 393.4 1032.04577 47.3 393.86 1033.18041 51 394.31 1034.29038 48.8 394.77 1035.42501 49.6 395.23 1036.55965 45.23 395.68 1037.66962 51.17 396.14 1038.80426 47.3 396.6 1039.93889 46.93 397.05 1041.04886 42.93 397.51 1042.1835 43.53 397.97 1043.31813 46.5 398.42 1044.4281 44.07 398.88 1045.56274 45.63 399.33 1046.67271 45.7 399.79 1047.80735 47.5 400.25 1048.94198 47.93 400.7 1050.05195 45.07 401.16 1051.18659 49.93 401.62 1052.32122 43.43

PAGE 154

144 Appendix A (Continued) Depth Age BP Ti (cps) 402.07 1053.43119 44.17 402.53 1054.56583 44.3 402.99 1055.70047 43.43 403.67 1057.37775 37.77 404.63 1059.74569 40.93 405.59 1062.11363 42.33 406.55 1064.48156 40.4 407.51 1066.8495 44.9 408.46 1069.19277 39.43 409.42 1071.5607 47.7 410.38 1073.92864 45.1 411.34 1076.29658 43 412.3 1078.66451 44.93 413.26 1081.03245 43.83 414.22 1083.40038 44.03 415.18 1085.76832 47.17 416.14 1088.13626 43.5 417.1 1090.50419 48.8 418.05 1092.84746 49.97 419.01 1095.2154 50.13 419.97 1097.58333 43.83 420.93 1099.95127 42.77 421.89 1102.31921 49.6 422.85 1104.68714 42.17 423.81 1107.05508 39.03 424.77 1109.42301 44.1 425.73 1111.79095 44 426.69 1114.15889 42.07 427.64 1116.50216 41.8 428.6 1118.87009 45.63 429.56 1121.23803 47.6 430.52 1123.60596 44.9 431.48 1125.9739 40.03 432.44 1128.34184 49 433.19 1130.19179 46.03 433.79 1131.67175 47.33 434.39 1133.15171 45.4 434.99 1134.63167 48.47 435.59 1136.11163 49.93

PAGE 155

145 Appendix A (Continued) Depth Age BP Ti (cps) 436.19 1137.59159 45.83 436.79 1139.07155 44 437.4 1140.57617 48.07 438 1142.05613 47.2 438.6 1143.53609 47.23 439.2 1145.01605 46.3 439.8 1146.49601 51 440.4 1147.97597 49.6 441 1149.45593 48.43 441.6 1150.93589 53.27 442.2 1152.41585 48.63 442.8 1153.89581 51.47 443.4 1155.37577 47 444 1156.85573 54.6 444.6 1158.33569 51.37 445.2 1159.81565 55.03 445.8 1161.29561 56.47 446.4 1162.77557 59 447 1164.25553 48.6 447.6 1165.73549 50.77 448.2 1167.21545 49.23 448.81 1168.72008 50.43 449.41 1170.20004 60.83 450.01 1171.68 54.77 450.61 1173.15996 52.83 451.21 1174.63992 51.93 451.81 1176.11988 54.63 452.41 1177.59984 51.57 453.01 1179.0798 59.73 453.61 1180.55976 54.17 454.21 1182.03972 55 454.81 1183.51968 55.57 455.41 1184.99964 51.6 456.01 1186.4796 54.43 456.61 1187.95956 53.43 457.21 1189.43952 53.57 457.81 1190.91948 53.83 458.41 1192.39944 53.43 459.01 1193.8794 55.97

PAGE 156

146 Appendix A (Continued) Depth Age BP Ti (cps) 459.61 1195.35936 59.17 460.22 1196.86398 55.53 460.82 1198.34394 53.9 461.42 1199.8239 57.27 462.02 1201.30386 55.87 462.62 1202.78382 52.2 463.22 1204.26378 48.5 463.82 1205.74374 51.23 464.42 1207.2237 55.16 465.02 1208.70366 47.17 465.62 1210.18362 47.1 466.22 1211.66358 55 466.82 1213.14354 49.6 467.42 1214.6235 48.23 468.02 1216.10346 54.53 468.62 1217.58342 50.73 469.22 1219.06338 49.97 469.82 1220.54334 48.33 470.42 1222.0233 49.17 471.02 1223.50326 53.87 471.63 1225.00789 51.57 472.23 1226.48785 51.9 472.83 1227.96781 57.3 473.43 1229.44777 61.47 474.03 1230.92773 56.57 474.63 1232.40769 57.17 475.23 1233.88765 55.27 475.83 1235.36761 56.5 476.43 1236.84757 57.8 477.03 1238.32753 53.5 477.63 1239.80749 52.6 478.23 1241.28745 55.37 478.83 1242.76741 56.23 479.43 1244.24737 56.63 480.03 1245.72733 53.03 480.63 1247.20729 48.13 481.23 1248.68725 59.27 481.83 1250.16721 55.4 482.43 1251.64717 56.8

PAGE 157

147 Appendix A (Continued) Depth Age BP Ti (cps) 483.04 1253.1518 52.37 483.64 1254.63176 54.3 484.24 1256.11172 58.5 484.84 1257.59168 62.7 485.44 1259.07164 54.13 486.04 1260.5516 59.87 486.64 1262.03156 52.93 487.24 1263.51152 55.23 487.84 1264.99148 57.4 488.44 1266.47144 59.93 489.04 1267.9514 65.6 489.64 1269.43136 63.6 490.24 1270.91132 58.3 490.84 1272.39128 52.87 491.44 1273.87124 57.3 492.04 1275.3512 58.2 492.64 1276.83116 60.2 493.14 1278.06446 57.47 493.45 1278.8291 55.23 493.75 1279.56908 53.33 494.05 1280.30906 51.47 494.36 1281.07371 47.27 494.66 1281.81369 47.47 494.96 1282.55367 54.47 495.27 1283.31831 57.37 495.57 1284.05829 54.17 495.87 1284.79827 50.1 496.17 1285.53825 55.17 496.48 1286.3029 46.8 496.78 1287.04288 54.7 497.08 1287.78286 54.9 497.39 1288.54751 48.67 497.69 1289.28749 50.63 497.99 1290.02747 52 498.3 1290.79211 50.77 498.6 1291.53209 51.27 498.9 1292.27207 50.13 499.21 1293.03672 50.67 499.51 1293.7767 52.2

PAGE 158

148 Appendix A (Continued) Depth Age BP Ti (cps) 499.81 1294.51668 48.73 500.12 1295.28132 59.6 500.42 1296.0213 51.97 500.72 1296.76128 47.17 501.03 1297.52593 44.7 501.33 1298.26591 49.7 501.63 1299.00589 53.13 501.93 1299.74587 50.73 502.24 1300.51052 49.87 502.54 1301.2505 53.6 502.84 1301.99048 53.43 503.09 1302.60713 50.77 503.39 1303.34711 50.23 503.69 1304.08709 49.9 504 1304.85173 48.4 504.3 1305.59171 46.47 504.6 1306.33169 49.83 504.91 1307.09634 52.93 505.21 1307.83632 49.97 505.51 1308.5763 45.87 505.82 1309.34094 47.97 506.12 1310.08092 44.77 506.42 1310.8209 42.87 506.72 1311.56088 45.87 507.03 1312.32553 47.43 507.33 1313.06551 46.03 507.63 1313.80549 48.6 507.94 1314.57014 48.1 508.24 1315.31012 47.47 508.54 1316.0501 45.17 508.85 1316.81474 47 509.15 1317.55472 44.83 509.45 1318.2947 45.4 509.76 1319.05935 45.07 510.06 1319.79933 42.67 510.36 1320.53931 45.8 511.58 1323.54856 48.8 511.88 1324.28854 42.17 512.18 1325.02852 47.57

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149 Appendix A (Continued) Depth Age BP Ti (cps) 512.48 1325.7685 46.67 512.79 1326.53315 41.8 513.09 1327.27313 43.6 513.39 1328.01311 45.07 513.7 1328.77775 39.13 514 1329.51773 43.73 514.3 1330.25771 40.13 514.61 1331.02236 42.5 514.91 1331.76234 44.67 515.21 1332.50232 40.43 515.52 1333.26696 41.33 515.82 1334.00694 37.83 516.12 1334.74692 46.4 516.43 1335.51157 45.53 516.73 1336.25155 43.93 517.03 1336.99153 39.87 517.34 1337.75618 38.73 517.64 1338.49616 43.53 517.94 1339.23614 44.57 518.24 1339.97612 47.53 518.55 1340.74076 50.5 518.85 1341.48074 49.53 519.15 1342.22072 47.67 519.46 1342.98537 47.97 519.76 1343.72535 45.57 520.06 1344.46533 46.9 520.37 1345.22997 47.63 520.67 1345.96995 49.03 520.97 1346.70993 37.3 521.28 1347.47458 48.33 521.58 1348.21456 46.6 521.88 1348.95454 48.9 522.19 1349.71919 50.27 522.49 1350.45917 60.07 522.79 1351.19915 44.47 523.1 1351.96379 47.2 523.4 1352.70377 43.2 523.7 1353.44375 48.2 524 1354.18373 44.17

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150 Appendix A (Continued) Depth Age BP Ti (cps) 524.31 1354.94838 46.33 524.61 1355.68836 45.13 524.91 1356.42834 46.2 525.22 1357.19298 45.77 525.52 1357.93296 40.2 525.82 1358.67294 38.5 526.13 1359.43759 45.63 526.43 1360.17757 46.37 526.73 1360.91755 46.3 527.04 1361.6822 46.1 527.34 1362.42218 50.03 527.64 1363.16216 49.23 527.95 1363.9268 45.03 528.25 1364.66678 46.2 528.55 1365.40676 49.17 528.86 1366.17141 50.87 529.16 1366.91139 50.1 529.46 1367.65137 49.3 529.76 1368.39135 51.7 530.07 1369.15599 52.1 530.37 1369.89597 46.2 530.67 1370.63595 53.43 530.98 1371.4006 53.47 531.28 1372.14058 47.5 531.58 1372.88056 49.3 531.89 1373.64521 50.8 532.19 1374.38519 46.77 532.49 1375.12517 49.9 532.8 1375.88981 47.4 533.1 1376.62979 45.63 533.4 1377.36977 48.4 533.71 1378.13442 48.7 534.01 1378.8744 51.07 534.31 1379.61438 47.1 534.62 1380.37902 46.3 534.92 1381.119 48.63 535.22 1381.85898 45.2 535.52 1382.59896 43.53 535.83 1383.36361 46.8

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151 Appendix A (Continued) Depth Age BP Ti (cps) 536.13 1384.10359 46.33 536.43 1384.84357 48.97 536.74 1385.60822 47.23 537.04 1386.3482 50.2 537.34 1387.08818 46.4 537.65 1387.85282 52.17 537.95 1388.5928 44.87 538.25 1389.33278 46.6 538.56 1390.09743 49.9 538.86 1390.83741 39.73 539.16 1391.57739 48.53 539.47 1392.34203 49.73 539.77 1393.08201 47.63 540.07 1393.82199 48.8 540.38 1394.58664 49.53 540.68 1395.32662 53.43 540.98 1396.0666 54.4 541.28 1396.80658 55.93 541.59 1397.57123 50.27 541.89 1398.31121 50.73 542.19 1399.05119 59.83 542.5 1399.81583 53.33 542.8 1400.55581 53.53 543.1 1401.29579 54.53 543.41 1402.06044 54.57 543.71 1402.80042 48.8 544.01 1403.5404 51.73 544.32 1404.30504 55.16 544.62 1405.04502 53.4 544.92 1405.785 50.07 545.23 1406.54965 52.9 545.53 1407.28963 50.3 545.83 1408.02961 49.13 546.14 1408.79426 55 546.44 1409.53424 49.63 546.74 1410.27422 50.1 547.04 1411.0142 49.93 547.35 1411.77884 50.33 547.65 1412.51882 45.67

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152 Appendix A (Continued) Depth Age BP Ti (cps) 547.95 1413.2588 54.03 548.26 1414.02345 49.83 548.56 1414.76343 46.3 548.86 1415.50341 51.93 549.17 1416.26805 47.27 549.47 1417.00803 51.33 549.77 1417.74801 48.8 550.08 1418.51266 48.43 550.38 1419.25264 54 550.68 1419.99262 57.53 550.99 1420.75727 47.9 551.29 1421.49725 49.43 551.59 1422.23723 57.17 551.9 1423.00187 52.57 552.2 1423.74185 53.13 552.5 1424.48183 54 552.8 1425.22181 54.83 553.11 1425.98646 49.77 553.41 1426.72644 43 553.71 1427.46642 52 554.02 1428.23106 48.73 554.32 1428.97104 43.63 554.62 1429.71102 49.87 554.93 1430.47567 47.7 555.23 1431.21565 47.3 555.53 1431.95563 49.8 555.84 1432.72028 48.67 556.14 1433.46026 51.53 556.44 1434.20024 49.67 556.75 1434.96488 49.73 557.05 1435.70486 51.97 557.35 1436.44484 49.87 557.66 1437.20949 46.07 557.96 1437.94947 46 558.26 1438.68945 44.67 558.56 1439.42943 47.93 558.87 1440.19407 46.67 559.17 1440.93405 49.67 559.47 1441.67403 49.83

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153 Appendix A (Continued) Depth Age BP Ti (cps) 559.78 1442.43868 46.8 560.08 1443.17866 52.63 560.38 1443.91864 43.53 560.69 1444.68329 45.6 560.99 1445.42327 49.9 561.29 1446.16325 48.53 561.6 1446.92789 51.17 561.9 1447.66787 50.87 562.2 1448.40785 45.3 562.51 1449.1725 45.67 562.81 1449.91248 48.03 563.11 1450.65246 50.67 563.42 1451.4171 50.5 563.72 1452.15708 44.37 564.02 1452.89706 47.33 564.32 1453.63704 51.73 564.63 1454.40169 48.23 564.93 1455.14167 43.03 565.23 1455.88165 46.6 565.54 1456.6463 45.67 565.84 1457.38628 48.73 566.14 1458.12626 50.63 566.45 1458.8909 39.7 566.75 1459.63088 48.6 567.05 1460.37086 50.57 567.36 1461.13551 49.23 567.66 1461.87549 45.4 567.96 1462.61547 51.4 568.27 1463.38011 46.43 568.57 1464.12009 50.9 568.87 1464.86007 48.8 569.18 1465.62472 51.83 569.48 1466.3647 48.8 569.78 1467.10468 52.47 570.08 1467.84466 47 570.38 1468.58466 49.5 570.68 1469.32466 53.4 570.98 1470.06466 39.43 571.28 1470.80466 52.93

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154 Appendix A (Continued) Depth Age BP Ti (cps) 571.58 1471.54466 56.93

PAGE 165

155 Appendix B: Organic Analyses

PAGE 166

156 Appendix B: Organic Analysis Abbreviations used in Appendix B tables: Depth: Depth in the core (mm) Age BP: Calendar Age BP %TOC: Weight percent of total organic carbon C16 ( g/g): Low molecular weight C16 n-alkane concentration ( g/g) C17 ( g/g): Low molecular weight C17 n-alkane concentration ( g/g) C18 ( g/g): Low molecular weight C18 n-alkane concentration ( g/g) C25 ( g/g): High molecular weight C25 n-alkane concentration ( g/g) C27 ( g/g): High molecular weight C27 n-alkane concentration ( g/g) C29 ( g/g): High molecular weight C29 n-alkane concentration ( g/g) C31 ( g/g): High molecular weight C31 n-alkane concentration ( g/g)

PAGE 167

157 Appendix B (Continued) Table 6. Total organic carbon concentrations. Depth Age BP %TOC 0 74.0 1.063448 5 86.3 1.378932 10 98.7 0.977728 15 111.0 1.535495 20 123.3 0.531572 25 135.7 1.104899 30 148.0 1.158165 40 172.7 1.24772 45 185.0 0.677068 50 197.3 1.464393 55 209.7 0.790527 60 222.0 0.827759 65 234.3 1.187852 70 246.7 0.578208 75 259.0 1.049324 80 271.3 0.748662 85 283.7 0.763359 90 296.0 0.569463 95 308.3 0.660874 100 320.7 0.606812 105 333.0 0.807056 110 345.3 0.682632 115 357.7 0.776908 120 370.0 0.499976 125 382.3 1.021852 130 394.7 0.607932 135 407.0 0.999222 140 419.3 0.567565 145 431.7 0.691517 150 444.0 0.527822 155 456.3 0.796295 160 468.7 0.533984 165 481.0 0.70626 170 493.3 0.538252 175 505.7 0.417699 180 518.0 0.557153

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158 Appendix B (Continued) Depth Age BP %TOC 185 530.3 0.84275 190 542.7 0.700965 195 555.0 0.834802 200 567.3 0.75561 205 579.7 0.572076 210 592.0 0.659536 215 604.3 0.862943 220 616.7 0.655349 225 629.0 1.198646 230 641.3 0.790903 235 653.6 1.105379 240 666.0 0.743352 245 678.3 0.515309 250 690.6 0.583012 255 703.0 0.827775 260 715.3 0.454476 265 727.6 0.727185 270 740.0 0.646791 275 752.3 0.497165 280 764.6 0.358859 285 777.0 0.870284 290 789.3 0.2537 295 801.6 1.015361 300 814.0 0.775324 305 826.3 0.692255 310 838.6 0.509038 315 851.0 0.715516 320 863.3 0.628668 325 875.6 0.784773 330 888.0 0.876206 335 900.3 0.39682 340 912.6 0.881213 345 925.0 0.418768 350 937.3 0.69731 355 949.6 0.966204 360 962.0 0.634516 365 974.3 0.86652 370 986.6 0.699678 375 999.0 0.865175

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159 Appendix B (Continued) Depth Age BP %TOC 380 1011.3 0.599292 385 1023.6 0.844419 390 1036.0 0.7378 395 1048.3 0.994881 400 1060.6 0.703879 405 1073.0 0.977576 410 1085.3 0.740274 415 1097.6 1.000607 420 1110.0 0.605245 425 1122.3 1.148188 430 1134.6 0.560299 435 1147.0 1.048606 440 1159.3 0.376942 445 1171.6 0.893909 450 1184.0 0.968452 455 1196.3 1.242432 460 1208.6 1.091095 465 1221.0 0.431459 470 1233.3 0.788031 475 1245.6 1.375931 480 1258.0 1.15851 485 1270.3 1.294257 490 1282.6 1.082996 495 1295.0 1.195048 500 1307.3 0.826035 505 1319.6 1.072954 510 1332.0 0.887453 515 1344.3 1.134522 520 1356.6 0.930763 525 1369.0 0.928958 530 1381.3 0.829311 535 1393.6 1.122849 540 1406.0 0.63281 545 1418.3 0.862015 550 1430.6 0.775794 555 1443.0 0.96667 560 1455.3 1.470806 565 1467.6 1.311991 570 1480.0 0.864996

PAGE 170

160 Appendix B (Continued) Depth Age BP %TOC 575 1492.3 1.302621

PAGE 171

161 Appendix B (Continued) Table 7. High molecular weight n-alkane concentrati ons. Depth Age BP C25 (g/g) C27 (g/g) C29 (g/g) C31 (g/g) 0 73.998 7447.691598 7051.322759 6169.21834 4085.27 914 5 86.3 8563.347113 7556.121854 6173.51291 3739.1229 4 10 98.664 6069.946479 4708.109488 3024.949636 1948. 77162 15 110.997 23475.36766 19351.04185 13231.34146 8253 .35106 20 123.33 9336.237638 9379.160296 7950.336118 7933. 79575 25 135.663 16947.21481 20457.2578 15816.49046 10230 .5547 50 197.328 21706.20621 22779.5639 18062.13256 9962. 9946 55 209.661 6306.330177 8777.681898 8873.35894 6148. 39439 60 221.994 7448.935769 6708.016832 5696.912016 5734 .53671 70 246.66 3396.914696 3363.146339 2689.618956 2277. 77161 75 258.993 1343.873213 1739.212261 1805.067732 1576 .61295 80 271.326 4440.780476 5027.642759 4075.468707 2808 .45286 85 283.659 4665.381168 4364.717959 3115.687076 2286 .14409 90 295.992 3724.267167 4628.235239 3524.548269 2696 .28133 95 308.325 5137.732229 6667.222996 5256.970438 5031 .99903 100 320.658 4452.917963 4465.423851 4017.916256 254 0.48826 105 332.991 4643.640651 4235.512506 3695.658545 262 7.85983 110 345.324 4827.223254 4429.944301 3330.797041 193 8.66016 115 357.657 6125.053669 5330.012136 3757.870998 231 1.46732 120 369.99 4588.838706 4929.32747 2817.497564 3653. 00614 125 382.323 4386.68452 4047.189323 3251.005606 2034 .14971 135 406.989 2638.492953 2659.557964 2196.453725 164 6.13031 150 443.988 3911.612736 4619.661063 3443.3811 2159. 45781 155 456.321 8288.85965 8406.36985 7399.786949 7163. 13577 160 468.654 4172.879952 3962.42473 3427.048383 3125 .85287 170 493.32 7808.011616 5944.282781 4045.709902 3434 .20845 180 517.986 3206.906189 3163.604384 2268.530608 136 3.19176 185 530.319 10551.86699 7264.820445 4391.522592 387 2.96621 190 542.652 4884.625059 5210.394656 4098.541693 354 2.91043 195 554.985 5970.010439 6150.669328 4997.131538 646 2.60735 200 567.318 7641.877425 6891.641741 5584.464515 356 0.71282 205 579.651 2848.5575 2945.90596 2470.847415 1536.7 2883 210 591.984 4240.121404 3539.059841 2529.154274 161 2.29216 220 616.65 1878.957881 1688.54907 1338.298124 1360. 49694 225 628.983 12120.07213 14552.81425 10886.86355 638 6.5836 235 653.649 10540.11963 11224.948 8973.97605 8989.3 025

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162 Appendix B (Continued) Depth Age BP C25 (g/g) C27 (g/g) C29 (g/g) C31 (g/g) 250 690.648 4924.604414 4657.414471 3580.035172 224 7.89914 255 702.981 6248.890924 7273.657673 6678.40097 4880 .92715 260 715.314 4927.285781 4863.620373 4619.316796 386 1.12126 270 739.98 11295.42076 11336.13062 9290.582192 7842 .92573 275 752.313 1524.338254 1957.02283 1871.801523 1800 .78126 280 764.646 1231.633373 1308.933318 964.83624 573.5 02032 285 776.979 9294.32821 6738.686447 4400.492263 4339 .9297 290 789.312 2387.282276 2737.447789 2119.014906 206 7.87148 295 801.645 1813.97304 2016.072561 1347.600889 1194 .77712 300 813.978 8437.693367 7575.553481 6116.439735 387 2.71904 305 826.311 4564.872812 4007.539501 3101.693258 183 5.83881 310 838.644 5165.199033 3480.974135 2775.22603 1640 .64162 315 850.977 1626.469879 1428.181705 1067.151508 669 .0246 320 863.31 7117.539649 6883.285749 5653.34168 5945. 11479 325 875.643 2516.171757 2859.624966 2104.618119 122 0.9081 335 900.309 2104.512214 2154.593558 1669.733302 180 6.31398 350 937.308 3501.973137 3639.566361 2753.629399 0 355 949.641 9778.954761 10445.06436 9700.344718 988 9.43166 360 961.974 9826.881787 6916.023027 4801.489116 351 2.72116 370 986.64 2393.528494 2358.052658 1836.01957 1608. 5241 380 1011.306 4834.84129 5516.588385 4397.941653 2889.8218 385 1023.639 3473.953644 3758.202412 3101.838413 2846.69065 390 1035.972 4203.620453 5214.366724 4158.79059 3626.77174 395 1048.305 13280.1653 13966.77668 11308.64249 9912.31888 400 1060.638 3292.766944 3765.076722 3221.019091 2249.19198 405 1072.971 6036.275316 5499.768199 4384.720849 2592.13319 410 1085.304 4601.643659 3888.861573 3374.907171 2570.96757 415 1097.637 10246.91289 8479.261223 6903.979839 4758.60495 420 1109.97 7861.310999 7656.47175 6380.15791 7050. 59818 425 1122.303 10244.25219 12237.86386 8794.927764 724.978446 435 1146.969 5985.540682 6309.408734 5018.335275 5537.28794 450 1183.968 6096.232545 6855.729681 5336.240569 3246.23377 455 1196.301 11271.15588 11101.64776 10478.07187 10587.059 460 1208.634 15767.08258 14114.94241 11693.63124 11361.9709 470 1233.3 3066.020685 3087.268217 2487.046961 1902 .05913 475 1245.633 7906.688941 8913.911164 8431.647765 7947.04917 480 1257.966 5160.666178 5689.237575 4598.835442 3141.38113 485 1270.299 8310.004686 8873.547557 6980.758321 6202.06742 490 1282.632 8994.123322 10731.87202 8233.864621 7435.265

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163 Appendix B (Continued) Depth Age BP C25 (g/g) C27 (g/g) C29 (g/g) C31 (g/g) 495 1294.965 4633.215414 5715.680884 4435.392 5254.42544 500 1307.298 7222.632779 6795.724446 5496.103628 3430.92618 505 1319.631 1326.005628 1533.2758 1351.344188 896.147482 510 1331.964 6666.080574 5484.312163 3982.931955 2611.04433 515 1344.297 6912.224385 5782.086092 4517.101753 2950.37932 525 1368.963 3196.735933 3743.505488 2772.719074 1709.41062 535 1393.629 11115.69931 11352.21511 8914.285623 8437.82429 550 1430.628 15459.57676 15224.87278 11278.08664 0 555 1442.961 8898.362614 8821.135708 8447.427265 8343.3365 560 1455.294 13655.33881 12681.14109 10001.88543 8546.39952 570 1479.96 15066.65989 15258.38575 12571.49397 951 6.80916

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164 Appendix B (Continued) Table 8. Low molecular weight n-alkane concentratio ns. Depth Age BP C16 (g/g) C17 (g/g) C18 (g/g) 0 73.998 406.116715 422.318359 442.48638 5 86.3 481.859259 1220.70092 448.01455 10 98.664 330.604993 651.268768 313.43213 15 110.997 1150.29158 784.807492 0 20 123.33 438.26206 895.582571 0 25 135.663 1516.95936 3566.51407 0 50 197.328 1369.75559 1212.14718 1233.0048 55 209.661 0 1425.10725 0 60 221.994 456.942053 788.421297 0 70 246.66 78.2982754 656.138757 0 80 271.326 271.834386 902.318207 0 90 295.992 876.367642 1582.36963 0 95 308.325 269.811894 1022.63226 401.30554 100 320.658 0 182.836982 451.22798 105 332.991 290.454895 300.281125 0 110 345.324 309.655215 332.385404 0 115 357.657 246.256102 246.418065 0 120 369.99 355.09508 198.42345 0 125 382.323 455.209792 1070.24102 440.50751 135 406.989 0 492.770796 0 150 443.988 0 657.153111 0 155 456.321 409.968532 1263.05432 277.96948 160 468.654 298.873586 155.309531 0 170 493.32 212.552747 812.095648 0 180 517.986 215.006196 728.743902 0 185 530.319 539.188149 1076.48787 0 190 542.652 1081.74105 1062.21996 455.62723 195 554.985 935.29952 3526.28724 0 200 567.318 684.507237 403.668929 209.32776 205 579.651 125.321598 428.081126 0 210 591.984 265.32328 537.772399 0 225 628.983 362.650736 3403.86908 0 235 653.649 659.719086 721.973515 0 250 690.648 512.598517 437.286145 26870.999 255 702.981 353.457807 775.811539 0 260 715.314 262.063976 320.986302 0

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165 Appendix B (Continued) Depth Age BP C16 (g/g) C17 (g/g) C18 (g/g) 270 739.98 400.749369 3032.75539 0 275 752.313 275.067257 1147.91658 0 280 764.646 66.5854089 464.182704 56.605879 285 776.979 465.861263 658.610393 0 290 789.312 279.941015 201.907302 0 300 813.978 404.033199 327.774082 450.31518 305 826.311 315.620209 521.160686 309.23221 310 838.644 308.254247 330.798601 315.80605 320 863.31 210.915607 1304.3671 0 325 875.643 506.538415 673.591322 297.95879 335 900.309 133.640935 116.07808 148.9971 350 937.308 251.701517 218.623349 280.62356 355 949.641 528.820712 2678.98797 0 360 961.974 491.365796 437.001853 0 380 1011.31 406.241528 2325.39594 0 385 1023.64 310.258459 2207.47356 0 390 1035.97 243.84819 1136.3266 0 395 1048.31 463.467765 802.521861 1084.8106 400 1060.64 169.489651 789.817626 131.23519 405 1072.97 311.349201 539.119564 312.61643 410 1085.3 391.902793 567.54691 351.37487 415 1097.64 645.793207 639.928865 291.6665 420 1109.97 541.911708 2798.54567 0 425 1122.3 798.052809 2881.28031 0 435 1146.97 479.143969 3165.90119 895.08588 450 1183.97 1152.51567 913.227472 570.97954 455 1196.3 919.943929 1243.2321 0 460 1208.63 1056.69695 1858.12081 0 470 1233.3 272.530194 5260.61681 1245.5397 480 1257.97 353.167012 1125.14554 0 485 1270.3 541.041427 1640.2143 0 490 1282.63 566.698086 4009.19382 1452.5309 495 1294.97 748.859074 1321.16958 0 500 1307.3 484.833641 403.657674 207.10833 510 1331.96 964.902153 1294.14699 316.39395 515 1344.3 569.744612 489.639639 658.53833 525 1368.96 278.075742 1080.91404 0 535 1393.63 1425.13929 5321.79228 735.42322 550 1430.63 2701.06885 908.179749 988.29065

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166 Appendix B (Continued) Depth Age BP C16 (g/g) C17 (g/g) C18 (g/g) 555 1442.96 803.832761 738.978537 302.96162 560 1455.29 2024.27606 1609.16124 0 570 1479.96 747.745746 1604.95341 418.36737

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167 Appendix C: Isotopic Analyses

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168 Appendix C: Isotopic Analyses Abbreviations used in Appendix C tables: Depth: Depth in the core (mm) Age BP: Calendar Age BP 13C ‰PDB: 13C (‰ PDB) of bulk organic carbon 15N ‰Air: 15N (‰ Air) of bulk organic nitrogen C25 D ‰SMOW: D (‰ SMOW) of high molecular weight n-alkane C25 C27 D ‰SMOW: D (‰ SMOW) of high molecular weight n-alkane C27 C29 D ‰SMOW: D (‰ SMOW) of high molecular weight n-alkane C29

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169 Appendix C (Continued) Table 9. Bulk organic 13C and 15N analyses. Depth Age BP 13C ‰PDB 15N ‰Air 0 73.998 -24.735 6.31 5 86.331 -23.33 3.64 10 98.664 -22.2350625 3.8 15 110.997 -22.93 3.565 20 123.33 -22.29 4.735 25 135.663 -22.285 0 30 147.996 -22.745 4.71 40 172.662 -22.71 3.095 45 184.995 -21.78 3.955 50 197.328 -22.28 2.295 55 209.661 -22.28 4.945 60 221.994 -22.64 5.13 65 234.327 -23.33 5.63 70 246.66 -23.825 3.21 75 258.993 -23.855 4.3 80 271.326 -23.52 4.03 85 283.659 -22.68 5.13 90 295.992 -25.355 3.77 95 308.325 -22.435 5.095 100 320.658 -22.9 2.98 105 332.991 -22.35 3.12 110 345.324 -22.435 5.325 115 357.657 -22.335 5.31 120 369.99 -22.465 4.79 125 382.323 -23.11 5.04 130 394.656 -22.93 4.185 135 406.989 -22.64 3.925 140 419.322 -22.57 4.44 145 431.655 -22.39 4.945 150 443.988 -22.52 4.48 155 456.321 -23.445 5.08 160 468.654 -23.09 3.585 165 480.987 -23.19 3.93 170 493.32 -23.01 4.3 175 505.653 -23.265 4.735 180 517.986 -23.74 4.21

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170 Appendix C (Continued) Depth Age BP 13C ‰PDB 15N ‰Air 185 530.319 -23.715 5.315 190 542.652 -23.485 3.785 195 554.985 -23.07 2.855 200 567.318 -22.795 4.02 205 579.651 -22.7 4.495 210 591.984 -22.575 4.66 215 604.317 -23.16 4.765 220 616.65 -22.73 3.44 225 628.983 -23.665 4.63 230 641.316 -22.505 4.585 235 653.649 -22.825 4.255 240 665.982 -22.725 4.105 245 678.315 -23.665 4.63 250 690.648 -23.15 3.53 255 702.981 -22.96 2.715 260 715.314 -22.575 3.945 265 727.647 -22.76 4.75 270 739.98 -23.18 4.48 275 752.313 -22.95 4.31 280 764.646 -23.165 3.97 285 776.979 -23.025 2.92 290 789.312 -22.535 3.775 295 801.645 -22.4 4.67 300 813.978 -22.775 4.225 305 826.311 -22.685 4.765 310 838.644 -23.98 4.83 315 850.977 -22.235 4.43 320 863.31 -22.28 4.075 325 875.643 -22.7 4.535 330 887.976 -22.995 4.165 335 900.309 -23.485 4.405 340 912.642 -23.505 4.955 345 924.975 -22.345 3.71 350 937.308 -23.165 3.815 355 949.641 -24.63 4.605 360 961.974 -24.69 4.27 365 974.307 -24.73 4.02 370 986.64 -23.59 3.55 375 998.973 -23.375 3.755

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171 Appendix C (Continued) Depth Age BP 13C ‰PDB 15N ‰Air 380 1011.306 -23.01 4.01 385 1023.639 -23.45 5.23 390 1035.972 -23.02 4.17 395 1048.305 -23.87 4.325 400 1060.638 -23.815 3.59 405 1072.971 -22.935 3.49 410 1085.304 -23.365 3.09 415 1097.637 -23.4 4.435 420 1109.97 -22.73 4.64 425 1122.303 -23.14 5.05 430 1134.636 -23.465 4.06 435 1146.969 -24.17 3.27 440 1159.302 -23.57 3.345 445 1171.635 -24.62 4.51 450 1183.968 -24.855 4.16 455 1196.301 -24.765 3.895 460 1208.634 -24.18 3.7 465 1220.967 -24.635 3.77 470 1233.3 -24.41 3.28 475 1245.633 -26.01 3.98 480 1257.966 -26.07 0 485 1270.299 -26.19 3.7 490 1282.632 -24.95 0 495 1294.965 -24.66 0 500 1307.298 -24.27 3.13 505 1319.631 -24.205 4.14 510 1331.964 -23.48 4.3 515 1344.297 -23.905 4.435 520 1356.63 -23.45 3.6 525 1368.963 -23.51 3.19 530 1381.296 -22.6 3.21 535 1393.629 -23.04 4.37 540 1405.962 -23.415 3.565 545 1418.295 -22.99 3.58 550 1430.628 -23.315 3.01 555 1442.961 -22.835 4.095 560 1455.294 -23.41 3.38 565 1467.627 -23.14 4.035 570 1479.96 -23.275 3.395

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172 Appendix C (Continued) Depth Age BP 13C ‰PDB 15N ‰Air 575 1492.293 -23.175 3.745

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173 Appendix C (Continued) Table 10. High molecular weight n-alkane D analyses. Depth Age BP C25 D ‰SMOW C27 D ‰SMOW C29 D ‰SMOW 0 73.998 -83.033 -92.371 -84.299 15 110.997 -84.674 -85.75 -81.294 50 197.328 -114.936 -122.39 -113.48 60 221.994 -76.185 -95.735 -92.96 70 246.66 -123.828 -132.071 -131.72 95 308.325 -58.388 -106.972 -111.126 105 332.991 -90.522 -97.279 -89.235 125 382.323 -97.337 -96.351 -92.937 135 406.989 -81.434 -94.327 -91.176 150 443.988 -114.112 -115.713 -96.347 160 468.654 -102.998 -102.828 -94.328 165 480.987 -83.155 -102.534 -95.408 185 530.319 -109.757 -113.203 -123.078 195 554.985 -75.599 -98.489 -112.53 200 567.318 -88.074 -96.904 -88.081 210 591.984 -84.67 -94.64 -87.896 225 628.983 -72.791 -78.676 -76.504 235 653.649 -105.61 -109.312 -119.499 265 727.647 -126.598 -128.261 -126.55 290 789.312 -100.348 -111.171 -132.19 295 801.645 -117.764 -117.291 -131.815 300 813.978 -88.689 -97.216 -91.423 310 838.644 -85.631 -91.276 -92.663 335 900.309 -100.902 -105.569 -112.856 350 937.308 -120.84 -124.805 -113.474 365 974.307 -112.879 -118.08 -122.01 370 986.64 -109.927 -120.217 -127.825 380 1011.306 -81.882 -87.006 -82.502 410 1085.304 -104.347 -99.6 -99.426 425 1122.303 -84.807 -88.3 -83.716 435 1146.969 -94.594 -104.021 -111.476 450 1183.968 -97.817 -109.68 -95.574 455 1196.301 -66.129 -88.555 -97.55 460 1208.634 -81.754 -85.904 -106.924 480 1257.966 -80.984 -63.592 -85.094 485 1270.299 -95.922 -109.576 -102.57

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174 Appendix C (Continued) Depth Age BP C25 D ‰SMOW C27 D ‰SMOW C29 D ‰SMOW 495 1294.965 -134.078 -127.372 -125.375 500 1307.298 -99.122 -98.071 -82.869 510 1331.964 -88.242 -93.346 -81.84 515 1344.297 -81.664 -95.915 -84.163 525 1368.963 -93.274 -96.709 -93.513 550 1430.628 -114.242 -119.204 -89.984 555 1442.961 -100.622 -94.878 -90.332 565 1467.627 -80.033 -96.527 -96.936

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About the Author Jennifer A. Flannery was born in Stoughton, MA on April 15, 1983. She was a member of the Bridgewater-Raynham Regional High Sch ool graduating class of 2001 in Bridgewater, MA. She went on to obtain a Bachelor o f Science degree in Marine Science with a Biology Concentration from Eckerd College in St. Petersburg, Florida in 2005. She began a Master of Science program at the Colleg e of Marine Science, USF in January, 2006 under the advisement of Dr. David Hol lander, which she finished in August, 2008. In her free time she enjoys dancing, watching Red Sox baseball, and playing catch with her dogs.


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A 1400 year multi-proxy record of hydrologic variability in the Gulf of Mexico :
b exploring ocean-continent linkages during the late Holocene.
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ABSTRACT: Late Holocene climate variability includes the Little Ice Age (LIA, 450-150 BP) and the Medieval Warm Period (MWP, 1100-700 BP) that are characterized by contrasting hydrologic and thermal regimes. The degree of interaction between the North American continent and the ocean during these two abrupt climate events is not well known. Marine sedimentary records from basins proximal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changing climate and hydrologic conditions. The Pigmy Basin in the northern Gulf of Mexico is ideally situated to record inputs from the Mississippi River and to relate these inputs to changing hydrologic conditions over North America during the LIA and MWP. Hydrologic variability recorded over the North America continent is directly dependent on the moisture balance (E/P) over the sub-tropical Gulf of Mexico (a major source of moisture to the North America continent). Warm, moist air masses from the south interact with cold/dry air masses from the north over the North American continent to produce storm fronts. Increased evaporation over the Gulf of Mexico leads to enhanced precipitation over the North American continent, due to the intensification of atmospheric circulation, which influences meridional moisture flux from the Gulf of Mexico to the North American continent. This study focuses on the sedimentary record spanning the last 1400 years and utilizes a multi-proxy approach incorporating organic and inorganic geochemical analyses to define intervals of varying continental inputs and to assess changes in the moisture balance (E-P) within the Gulf of Mexico.
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Ocean-continent interactions
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